libvpx: Pull from upstream

source/libvpx/third_party/nestegg/src/nestegg.c

Index: source/libvpx/third_party/nestegg/src/nestegg.c
===================================================================
--- source/libvpx/third_party/nestegg/src/nestegg.c	(revision 278778)
+++ source/libvpx/third_party/nestegg/src/nestegg.c	(working copy)
@@ -1,2323 +0,0 @@
-/*
- * Copyright © 2010 Mozilla Foundation
- *
- * This program is made available under an ISC-style license.  See the
- * accompanying file LICENSE for details.
- */
-#include <assert.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "third_party/nestegg/halloc/halloc.h"
-#include "third_party/nestegg/include/nestegg/nestegg.h"
-
-/* EBML Elements */
-#define ID_EBML                 0x1a45dfa3
-#define ID_EBML_VERSION         0x4286
-#define ID_EBML_READ_VERSION    0x42f7
-#define ID_EBML_MAX_ID_LENGTH   0x42f2
-#define ID_EBML_MAX_SIZE_LENGTH 0x42f3
-#define ID_DOCTYPE              0x4282
-#define ID_DOCTYPE_VERSION      0x4287
-#define ID_DOCTYPE_READ_VERSION 0x4285
-
-/* Global Elements */
-#define ID_VOID                 0xec
-#define ID_CRC32                0xbf
-
-/* WebM Elements */
-#define ID_SEGMENT              0x18538067
-
-/* Seek Head Elements */
-#define ID_SEEK_HEAD            0x114d9b74
-#define ID_SEEK                 0x4dbb
-#define ID_SEEK_ID              0x53ab
-#define ID_SEEK_POSITION        0x53ac
-
-/* Info Elements */
-#define ID_INFO                 0x1549a966
-#define ID_TIMECODE_SCALE       0x2ad7b1
-#define ID_DURATION             0x4489
-
-/* Cluster Elements */
-#define ID_CLUSTER              0x1f43b675
-#define ID_TIMECODE             0xe7
-#define ID_BLOCK_GROUP          0xa0
-#define ID_SIMPLE_BLOCK         0xa3
-
-/* BlockGroup Elements */
-#define ID_BLOCK                0xa1
-#define ID_BLOCK_DURATION       0x9b
-#define ID_REFERENCE_BLOCK      0xfb
-#define ID_DISCARD_PADDING      0x75a2
-
-/* Tracks Elements */
-#define ID_TRACKS               0x1654ae6b
-#define ID_TRACK_ENTRY          0xae
-#define ID_TRACK_NUMBER         0xd7
-#define ID_TRACK_UID            0x73c5
-#define ID_TRACK_TYPE           0x83
-#define ID_FLAG_ENABLED         0xb9
-#define ID_FLAG_DEFAULT         0x88
-#define ID_FLAG_LACING          0x9c
-#define ID_TRACK_TIMECODE_SCALE 0x23314f
-#define ID_LANGUAGE             0x22b59c
-#define ID_CODEC_ID             0x86
-#define ID_CODEC_PRIVATE        0x63a2
-#define ID_CODEC_DELAY          0x56aa
-#define ID_SEEK_PREROLL         0x56bb
-
-/* Video Elements */
-#define ID_VIDEO                0xe0
-#define ID_STEREO_MODE          0x53b8
-#define ID_PIXEL_WIDTH          0xb0
-#define ID_PIXEL_HEIGHT         0xba
-#define ID_PIXEL_CROP_BOTTOM    0x54aa
-#define ID_PIXEL_CROP_TOP       0x54bb
-#define ID_PIXEL_CROP_LEFT      0x54cc
-#define ID_PIXEL_CROP_RIGHT     0x54dd
-#define ID_DISPLAY_WIDTH        0x54b0
-#define ID_DISPLAY_HEIGHT       0x54ba
-
-/* Audio Elements */
-#define ID_AUDIO                0xe1
-#define ID_SAMPLING_FREQUENCY   0xb5
-#define ID_CHANNELS             0x9f
-#define ID_BIT_DEPTH            0x6264
-
-/* Cues Elements */
-#define ID_CUES                 0x1c53bb6b
-#define ID_CUE_POINT            0xbb
-#define ID_CUE_TIME             0xb3
-#define ID_CUE_TRACK_POSITIONS  0xb7
-#define ID_CUE_TRACK            0xf7
-#define ID_CUE_CLUSTER_POSITION 0xf1
-#define ID_CUE_BLOCK_NUMBER     0x5378
-
-/* EBML Types */
-enum ebml_type_enum {
-  TYPE_UNKNOWN,
-  TYPE_MASTER,
-  TYPE_UINT,
-  TYPE_FLOAT,
-  TYPE_INT,
-  TYPE_STRING,
-  TYPE_BINARY
-};
-
-#define LIMIT_STRING            (1 << 20)
-#define LIMIT_BINARY            (1 << 24)
-#define LIMIT_BLOCK             (1 << 30)
-#define LIMIT_FRAME             (1 << 28)
-
-/* Field Flags */
-#define DESC_FLAG_NONE          0
-#define DESC_FLAG_MULTI         (1 << 0)
-#define DESC_FLAG_SUSPEND       (1 << 1)
-#define DESC_FLAG_OFFSET        (1 << 2)
-
-/* Block Header Flags */
-#define BLOCK_FLAGS_LACING      6
-
-/* Lacing Constants */
-#define LACING_NONE             0
-#define LACING_XIPH             1
-#define LACING_FIXED            2
-#define LACING_EBML             3
-
-/* Track Types */
-#define TRACK_TYPE_VIDEO        1
-#define TRACK_TYPE_AUDIO        2
-
-/* Track IDs */
-#define TRACK_ID_VP8            "V_VP8"
-#define TRACK_ID_VP9            "V_VP9"
-#define TRACK_ID_VORBIS         "A_VORBIS"
-#define TRACK_ID_OPUS           "A_OPUS"
-
-enum vint_mask {
-  MASK_NONE,
-  MASK_FIRST_BIT
-};
-
-struct ebml_binary {
-  unsigned char * data;
-  size_t length;
-};
-
-struct ebml_list_node {
-  struct ebml_list_node * next;
-  uint64_t id;
-  void * data;
-};
-
-struct ebml_list {
-  struct ebml_list_node * head;
-  struct ebml_list_node * tail;
-};
-
-struct ebml_type {
-  union ebml_value {
-    uint64_t u;
-    double f;
-    int64_t i;
-    char * s;
-    struct ebml_binary b;
-  } v;
-  enum ebml_type_enum type;
-  int read;
-};
-
-/* EBML Definitions */
-struct ebml {
-  struct ebml_type ebml_version;
-  struct ebml_type ebml_read_version;
-  struct ebml_type ebml_max_id_length;
-  struct ebml_type ebml_max_size_length;
-  struct ebml_type doctype;
-  struct ebml_type doctype_version;
-  struct ebml_type doctype_read_version;
-};
-
-/* Matroksa Definitions */
-struct seek {
-  struct ebml_type id;
-  struct ebml_type position;
-};
-
-struct seek_head {
-  struct ebml_list seek;
-};
-
-struct info {
-  struct ebml_type timecode_scale;
-  struct ebml_type duration;
-};
-
-struct block_group {
-  struct ebml_type duration;
-  struct ebml_type reference_block;
-  struct ebml_type discard_padding;
-};
-
-struct cluster {
-  struct ebml_type timecode;
-  struct ebml_list block_group;
-};
-
-struct video {
-  struct ebml_type stereo_mode;
-  struct ebml_type pixel_width;
-  struct ebml_type pixel_height;
-  struct ebml_type pixel_crop_bottom;
-  struct ebml_type pixel_crop_top;
-  struct ebml_type pixel_crop_left;
-  struct ebml_type pixel_crop_right;
-  struct ebml_type display_width;
-  struct ebml_type display_height;
-};
-
-struct audio {
-  struct ebml_type sampling_frequency;
-  struct ebml_type channels;
-  struct ebml_type bit_depth;
-};
-
-struct track_entry {
-  struct ebml_type number;
-  struct ebml_type uid;
-  struct ebml_type type;
-  struct ebml_type flag_enabled;
-  struct ebml_type flag_default;
-  struct ebml_type flag_lacing;
-  struct ebml_type track_timecode_scale;
-  struct ebml_type language;
-  struct ebml_type codec_id;
-  struct ebml_type codec_private;
-  struct ebml_type codec_delay;
-  struct ebml_type seek_preroll;
-  struct video video;
-  struct audio audio;
-};
-
-struct tracks {
-  struct ebml_list track_entry;
-};
-
-struct cue_track_positions {
-  struct ebml_type track;
-  struct ebml_type cluster_position;
-  struct ebml_type block_number;
-};
-
-struct cue_point {
-  struct ebml_type time;
-  struct ebml_list cue_track_positions;
-};
-
-struct cues {
-  struct ebml_list cue_point;
-};
-
-struct segment {
-  struct ebml_list seek_head;
-  struct info info;
-  struct ebml_list cluster;
-  struct tracks tracks;
-  struct cues cues;
-};
-
-/* Misc. */
-struct pool_ctx {
-  char dummy;
-};
-
-struct list_node {
-  struct list_node * previous;
-  struct ebml_element_desc * node;
-  unsigned char * data;
-};
-
-struct saved_state {
-  int64_t stream_offset;
-  struct list_node * ancestor;
-  uint64_t last_id;
-  uint64_t last_size;
-  int last_valid;
-};
-
-struct frame {
-  unsigned char * data;
-  size_t length;
-  struct frame * next;
-};
-
-/* Public (opaque) Structures */
-struct nestegg {
-  nestegg_io * io;
-  nestegg_log log;
-  struct pool_ctx * alloc_pool;
-  uint64_t last_id;
-  uint64_t last_size;
-  int last_valid;
-  struct list_node * ancestor;
-  struct ebml ebml;
-  struct segment segment;
-  int64_t segment_offset;
-  unsigned int track_count;
-};
-
-struct nestegg_packet {
-  uint64_t track;
-  uint64_t timecode;
-  struct frame * frame;
-  int64_t discard_padding;
-};
-
-/* Element Descriptor */
-struct ebml_element_desc {
-  char const * name;
-  uint64_t id;
-  enum ebml_type_enum type;
-  size_t offset;
-  unsigned int flags;
-  struct ebml_element_desc * children;
-  size_t size;
-  size_t data_offset;
-};
-
-#define E_FIELD(ID, TYPE, STRUCT, FIELD) \
-  { #ID, ID, TYPE, offsetof(STRUCT, FIELD), DESC_FLAG_NONE, NULL, 0, 0 }
-#define E_MASTER(ID, TYPE, STRUCT, FIELD) \
-  { #ID, ID, TYPE, offsetof(STRUCT, FIELD), DESC_FLAG_MULTI, ne_ ## FIELD ## _elements, \
-      sizeof(struct FIELD), 0 }
-#define E_SINGLE_MASTER_O(ID, TYPE, STRUCT, FIELD) \
-  { #ID, ID, TYPE, offsetof(STRUCT, FIELD), DESC_FLAG_OFFSET, ne_ ## FIELD ## _elements, 0, \
-      offsetof(STRUCT, FIELD ## _offset) }
-#define E_SINGLE_MASTER(ID, TYPE, STRUCT, FIELD) \
-  { #ID, ID, TYPE, offsetof(STRUCT, FIELD), DESC_FLAG_NONE, ne_ ## FIELD ## _elements, 0, 0 }
-#define E_SUSPEND(ID, TYPE) \
-  { #ID, ID, TYPE, 0, DESC_FLAG_SUSPEND, NULL, 0, 0 }
-#define E_LAST \
-  { NULL, 0, 0, 0, DESC_FLAG_NONE, NULL, 0, 0 }
-
-/* EBML Element Lists */
-static struct ebml_element_desc ne_ebml_elements[] = {
-  E_FIELD(ID_EBML_VERSION, TYPE_UINT, struct ebml, ebml_version),
-  E_FIELD(ID_EBML_READ_VERSION, TYPE_UINT, struct ebml, ebml_read_version),
-  E_FIELD(ID_EBML_MAX_ID_LENGTH, TYPE_UINT, struct ebml, ebml_max_id_length),
-  E_FIELD(ID_EBML_MAX_SIZE_LENGTH, TYPE_UINT, struct ebml, ebml_max_size_length),
-  E_FIELD(ID_DOCTYPE, TYPE_STRING, struct ebml, doctype),
-  E_FIELD(ID_DOCTYPE_VERSION, TYPE_UINT, struct ebml, doctype_version),
-  E_FIELD(ID_DOCTYPE_READ_VERSION, TYPE_UINT, struct ebml, doctype_read_version),
-  E_LAST
-};
-
-/* WebM Element Lists */
-static struct ebml_element_desc ne_seek_elements[] = {
-  E_FIELD(ID_SEEK_ID, TYPE_BINARY, struct seek, id),
-  E_FIELD(ID_SEEK_POSITION, TYPE_UINT, struct seek, position),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_seek_head_elements[] = {
-  E_MASTER(ID_SEEK, TYPE_MASTER, struct seek_head, seek),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_info_elements[] = {
-  E_FIELD(ID_TIMECODE_SCALE, TYPE_UINT, struct info, timecode_scale),
-  E_FIELD(ID_DURATION, TYPE_FLOAT, struct info, duration),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_block_group_elements[] = {
-  E_SUSPEND(ID_BLOCK, TYPE_BINARY),
-  E_FIELD(ID_BLOCK_DURATION, TYPE_UINT, struct block_group, duration),
-  E_FIELD(ID_REFERENCE_BLOCK, TYPE_INT, struct block_group, reference_block),
-  E_FIELD(ID_DISCARD_PADDING, TYPE_INT, struct block_group, discard_padding),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_cluster_elements[] = {
-  E_FIELD(ID_TIMECODE, TYPE_UINT, struct cluster, timecode),
-  E_MASTER(ID_BLOCK_GROUP, TYPE_MASTER, struct cluster, block_group),
-  E_SUSPEND(ID_SIMPLE_BLOCK, TYPE_BINARY),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_video_elements[] = {
-  E_FIELD(ID_STEREO_MODE, TYPE_UINT, struct video, stereo_mode),
-  E_FIELD(ID_PIXEL_WIDTH, TYPE_UINT, struct video, pixel_width),
-  E_FIELD(ID_PIXEL_HEIGHT, TYPE_UINT, struct video, pixel_height),
-  E_FIELD(ID_PIXEL_CROP_BOTTOM, TYPE_UINT, struct video, pixel_crop_bottom),
-  E_FIELD(ID_PIXEL_CROP_TOP, TYPE_UINT, struct video, pixel_crop_top),
-  E_FIELD(ID_PIXEL_CROP_LEFT, TYPE_UINT, struct video, pixel_crop_left),
-  E_FIELD(ID_PIXEL_CROP_RIGHT, TYPE_UINT, struct video, pixel_crop_right),
-  E_FIELD(ID_DISPLAY_WIDTH, TYPE_UINT, struct video, display_width),
-  E_FIELD(ID_DISPLAY_HEIGHT, TYPE_UINT, struct video, display_height),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_audio_elements[] = {
-  E_FIELD(ID_SAMPLING_FREQUENCY, TYPE_FLOAT, struct audio, sampling_frequency),
-  E_FIELD(ID_CHANNELS, TYPE_UINT, struct audio, channels),
-  E_FIELD(ID_BIT_DEPTH, TYPE_UINT, struct audio, bit_depth),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_track_entry_elements[] = {
-  E_FIELD(ID_TRACK_NUMBER, TYPE_UINT, struct track_entry, number),
-  E_FIELD(ID_TRACK_UID, TYPE_UINT, struct track_entry, uid),
-  E_FIELD(ID_TRACK_TYPE, TYPE_UINT, struct track_entry, type),
-  E_FIELD(ID_FLAG_ENABLED, TYPE_UINT, struct track_entry, flag_enabled),
-  E_FIELD(ID_FLAG_DEFAULT, TYPE_UINT, struct track_entry, flag_default),
-  E_FIELD(ID_FLAG_LACING, TYPE_UINT, struct track_entry, flag_lacing),
-  E_FIELD(ID_TRACK_TIMECODE_SCALE, TYPE_FLOAT, struct track_entry, track_timecode_scale),
-  E_FIELD(ID_LANGUAGE, TYPE_STRING, struct track_entry, language),
-  E_FIELD(ID_CODEC_ID, TYPE_STRING, struct track_entry, codec_id),
-  E_FIELD(ID_CODEC_PRIVATE, TYPE_BINARY, struct track_entry, codec_private),
-  E_FIELD(ID_CODEC_DELAY, TYPE_UINT, struct track_entry, codec_delay),
-  E_FIELD(ID_SEEK_PREROLL, TYPE_UINT, struct track_entry, seek_preroll),
-  E_SINGLE_MASTER(ID_VIDEO, TYPE_MASTER, struct track_entry, video),
-  E_SINGLE_MASTER(ID_AUDIO, TYPE_MASTER, struct track_entry, audio),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_tracks_elements[] = {
-  E_MASTER(ID_TRACK_ENTRY, TYPE_MASTER, struct tracks, track_entry),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_cue_track_positions_elements[] = {
-  E_FIELD(ID_CUE_TRACK, TYPE_UINT, struct cue_track_positions, track),
-  E_FIELD(ID_CUE_CLUSTER_POSITION, TYPE_UINT, struct cue_track_positions, cluster_position),
-  E_FIELD(ID_CUE_BLOCK_NUMBER, TYPE_UINT, struct cue_track_positions, block_number),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_cue_point_elements[] = {
-  E_FIELD(ID_CUE_TIME, TYPE_UINT, struct cue_point, time),
-  E_MASTER(ID_CUE_TRACK_POSITIONS, TYPE_MASTER, struct cue_point, cue_track_positions),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_cues_elements[] = {
-  E_MASTER(ID_CUE_POINT, TYPE_MASTER, struct cues, cue_point),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_segment_elements[] = {
-  E_MASTER(ID_SEEK_HEAD, TYPE_MASTER, struct segment, seek_head),
-  E_SINGLE_MASTER(ID_INFO, TYPE_MASTER, struct segment, info),
-  E_MASTER(ID_CLUSTER, TYPE_MASTER, struct segment, cluster),
-  E_SINGLE_MASTER(ID_TRACKS, TYPE_MASTER, struct segment, tracks),
-  E_SINGLE_MASTER(ID_CUES, TYPE_MASTER, struct segment, cues),
-  E_LAST
-};
-
-static struct ebml_element_desc ne_top_level_elements[] = {
-  E_SINGLE_MASTER(ID_EBML, TYPE_MASTER, nestegg, ebml),
-  E_SINGLE_MASTER_O(ID_SEGMENT, TYPE_MASTER, nestegg, segment),
-  E_LAST
-};
-
-#undef E_FIELD
-#undef E_MASTER
-#undef E_SINGLE_MASTER_O
-#undef E_SINGLE_MASTER
-#undef E_SUSPEND
-#undef E_LAST
-
-static struct pool_ctx *
-ne_pool_init(void)
-{
-  struct pool_ctx * pool;
-
-  pool = h_malloc(sizeof(*pool));
-  if (!pool)
-    abort();
-  return pool;
-}
-
-static void
-ne_pool_destroy(struct pool_ctx * pool)
-{
-  h_free(pool);
-}
-
-static void *
-ne_pool_alloc(size_t size, struct pool_ctx * pool)
-{
-  void * p;
-
-  p = h_malloc(size);
-  if (!p)
-    abort();
-  hattach(p, pool);
-  memset(p, 0, size);
-  return p;
-}
-
-static void *
-ne_alloc(size_t size)
-{
-  void * p;
-
-  p = calloc(1, size);
-  if (!p)
-    abort();
-  return p;
-}
-
-static int
-ne_io_read(nestegg_io * io, void * buffer, size_t length)
-{
-  return io->read(buffer, length, io->userdata);
-}
-
-static int
-ne_io_seek(nestegg_io * io, int64_t offset, int whence)
-{
-  return io->seek(offset, whence, io->userdata);
-}
-
-static int
-ne_io_read_skip(nestegg_io * io, size_t length)
-{
-  size_t get;
-  unsigned char buf[8192];
-  int r = 1;
-
-  while (length > 0) {
-    get = length < sizeof(buf) ? length : sizeof(buf);
-    r = ne_io_read(io, buf, get);
-    if (r != 1)
-      break;
-    length -= get;
-  }
-
-  return r;
-}
-
-static int64_t
-ne_io_tell(nestegg_io * io)
-{
-  return io->tell(io->userdata);
-}
-
-static int
-ne_bare_read_vint(nestegg_io * io, uint64_t * value, uint64_t * length, enum vint_mask maskflag)
-{
-  int r;
-  unsigned char b;
-  size_t maxlen = 8;
-  unsigned int count = 1, mask = 1 << 7;
-
-  r = ne_io_read(io, &b, 1);
-  if (r != 1)
-    return r;
-
-  while (count < maxlen) {
-    if ((b & mask) != 0)
-      break;
-    mask >>= 1;
-    count += 1;
-  }
-
-  if (length)
-    *length = count;
-  *value = b;
-
-  if (maskflag == MASK_FIRST_BIT)
-    *value = b & ~mask;
-
-  while (--count) {
-    r = ne_io_read(io, &b, 1);
-    if (r != 1)
-      return r;
-    *value <<= 8;
-    *value |= b;
-  }
-
-  return 1;
-}
-
-static int
-ne_read_id(nestegg_io * io, uint64_t * value, uint64_t * length)
-{
-  return ne_bare_read_vint(io, value, length, MASK_NONE);
-}
-
-static int
-ne_read_vint(nestegg_io * io, uint64_t * value, uint64_t * length)
-{
-  return ne_bare_read_vint(io, value, length, MASK_FIRST_BIT);
-}
-
-static int
-ne_read_svint(nestegg_io * io, int64_t * value, uint64_t * length)
-{
-  int r;
-  uint64_t uvalue;
-  uint64_t ulength;
-  int64_t svint_subtr[] = {
-    0x3f, 0x1fff,
-    0xfffff, 0x7ffffff,
-    0x3ffffffffLL, 0x1ffffffffffLL,
-    0xffffffffffffLL, 0x7fffffffffffffLL
-  };
-
-  r = ne_bare_read_vint(io, &uvalue, &ulength, MASK_FIRST_BIT);
-  if (r != 1)
-    return r;
-  *value = uvalue - svint_subtr[ulength - 1];
-  if (length)
-    *length = ulength;
-  return r;
-}
-
-static int
-ne_read_uint(nestegg_io * io, uint64_t * val, uint64_t length)
-{
-  unsigned char b;
-  int r;
-
-  if (length == 0 || length > 8)
-    return -1;
-  r = ne_io_read(io, &b, 1);
-  if (r != 1)
-    return r;
-  *val = b;
-  while (--length) {
-    r = ne_io_read(io, &b, 1);
-    if (r != 1)
-      return r;
-    *val <<= 8;
-    *val |= b;
-  }
-  return 1;
-}
-
-static int
-ne_read_int(nestegg_io * io, int64_t * val, uint64_t length)
-{
-  int r;
-  uint64_t uval, base;
-
-  r = ne_read_uint(io, &uval, length);
-  if (r != 1)
-    return r;
-
-  if (length < sizeof(int64_t)) {
-    base = 1;
-    base <<= length * 8 - 1;
-    if (uval >= base) {
-        base = 1;
-        base <<= length * 8;
-    } else {
-      base = 0;
-    }
-    *val = uval - base;
-  } else {
-    *val = (int64_t) uval;
-  }
-
-  return 1;
-}
-
-static int
-ne_read_float(nestegg_io * io, double * val, uint64_t length)
-{
-  union {
-    uint64_t u;
-    float f;
-    double d;
-  } value;
-  int r;
-
-  /* Length == 10 not implemented. */
-  if (length != 4 && length != 8)
-    return -1;
-  r = ne_read_uint(io, &value.u, length);
-  if (r != 1)
-    return r;
-  if (length == 4)
-    *val = value.f;
-  else
-    *val = value.d;
-  return 1;
-}
-
-static int
-ne_read_string(nestegg * ctx, char ** val, uint64_t length)
-{
-  char * str;
-  int r;
-  const size_t alloc_size = (size_t)length + 1;
-
-  if (length == 0 || length > LIMIT_STRING)
-    return -1;
-  str = ne_pool_alloc(alloc_size, ctx->alloc_pool);
-  r = ne_io_read(ctx->io, (unsigned char *) str, alloc_size - 1);
-  if (r != 1)
-    return r;
-  str[alloc_size - 1] = '\0';
-  *val = str;
-  return 1;
-}
-
-static int
-ne_read_binary(nestegg * ctx, struct ebml_binary * val, uint64_t length)
-{
-  if (length == 0 || length > LIMIT_BINARY)
-    return -1;
-  val->length = (size_t)length;
-  val->data = ne_pool_alloc(val->length, ctx->alloc_pool);
-  return ne_io_read(ctx->io, val->data, val->length);
-}
-
-static int
-ne_get_uint(struct ebml_type type, uint64_t * value)
-{
-  if (!type.read)
-    return -1;
-
-  assert(type.type == TYPE_UINT);
-
-  *value = type.v.u;
-
-  return 0;
-}
-
-static int
-ne_get_uint32(struct ebml_type type, unsigned int * value)
-{
-  uint64_t v;
-  if (ne_get_uint(type, &v))
-    return -1;
-
-  assert((unsigned int)v == v);
-
-  *value = (unsigned int)v;
-
-  return 0;
-}
-
-static int
-ne_get_float(struct ebml_type type, double * value)
-{
-  if (!type.read)
-    return -1;
-
-  assert(type.type == TYPE_FLOAT);
-
-  *value = type.v.f;
-
-  return 0;
-}
-
-static int
-ne_get_string(struct ebml_type type, char ** value)
-{
-  if (!type.read)
-    return -1;
-
-  assert(type.type == TYPE_STRING);
-
-  *value = type.v.s;
-
-  return 0;
-}
-
-static int
-ne_get_binary(struct ebml_type type, struct ebml_binary * value)
-{
-  if (!type.read)
-    return -1;
-
-  assert(type.type == TYPE_BINARY);
-
-  *value = type.v.b;
-
-  return 0;
-}
-
-static int
-ne_is_ancestor_element(uint64_t id, struct list_node * ancestor)
-{
-  struct ebml_element_desc * element;
-
-  for (; ancestor; ancestor = ancestor->previous)
-    for (element = ancestor->node; element->id; ++element)
-      if (element->id == id)
-        return 1;
-
-  return 0;
-}
-
-static struct ebml_element_desc *
-ne_find_element(uint64_t id, struct ebml_element_desc * elements)
-{
-  struct ebml_element_desc * element;
-
-  for (element = elements; element->id; ++element)
-    if (element->id == id)
-      return element;
-
-  return NULL;
-}
-
-static void
-ne_ctx_push(nestegg * ctx, struct ebml_element_desc * ancestor, void * data)
-{
-  struct list_node * item;
-
-  item = ne_alloc(sizeof(*item));
-  item->previous = ctx->ancestor;
-  item->node = ancestor;
-  item->data = data;
-  ctx->ancestor = item;
-}
-
-static void
-ne_ctx_pop(nestegg * ctx)
-{
-  struct list_node * item;
-
-  item = ctx->ancestor;
-  ctx->ancestor = item->previous;
-  free(item);
-}
-
-static int
-ne_ctx_save(nestegg * ctx, struct saved_state * s)
-{
-  s->stream_offset = ne_io_tell(ctx->io);
-  if (s->stream_offset < 0)
-    return -1;
-  s->ancestor = ctx->ancestor;
-  s->last_id = ctx->last_id;
-  s->last_size = ctx->last_size;
-  s->last_valid = ctx->last_valid;
-  return 0;
-}
-
-static int
-ne_ctx_restore(nestegg * ctx, struct saved_state * s)
-{
-  int r;
-
-  r = ne_io_seek(ctx->io, s->stream_offset, NESTEGG_SEEK_SET);
-  if (r != 0)
-    return -1;
-  ctx->ancestor = s->ancestor;
-  ctx->last_id = s->last_id;
-  ctx->last_size = s->last_size;
-  ctx->last_valid = s->last_valid;
-  return 0;
-}
-
-static int
-ne_peek_element(nestegg * ctx, uint64_t * id, uint64_t * size)
-{
-  int r;
-
-  if (ctx->last_valid) {
-    if (id)
-      *id = ctx->last_id;
-    if (size)
-      *size = ctx->last_size;
-    return 1;
-  }
-
-  r = ne_read_id(ctx->io, &ctx->last_id, NULL);
-  if (r != 1)
-    return r;
-
-  r = ne_read_vint(ctx->io, &ctx->last_size, NULL);
-  if (r != 1)
-    return r;
-
-  if (id)
-    *id = ctx->last_id;
-  if (size)
-    *size = ctx->last_size;
-
-  ctx->last_valid = 1;
-
-  return 1;
-}
-
-static int
-ne_read_element(nestegg * ctx, uint64_t * id, uint64_t * size)
-{
-  int r;
-
-  r = ne_peek_element(ctx, id, size);
-  if (r != 1)
-    return r;
-
-  ctx->last_valid = 0;
-
-  return 1;
-}
-
-static void
-ne_read_master(nestegg * ctx, struct ebml_element_desc * desc)
-{
-  struct ebml_list * list;
-  struct ebml_list_node * node, * oldtail;
-
-  assert(desc->type == TYPE_MASTER && desc->flags & DESC_FLAG_MULTI);
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "multi master element %llx (%s)",
-           desc->id, desc->name);
-
-  list = (struct ebml_list *) (ctx->ancestor->data + desc->offset);
-
-  node = ne_pool_alloc(sizeof(*node), ctx->alloc_pool);
-  node->id = desc->id;
-  node->data = ne_pool_alloc(desc->size, ctx->alloc_pool);
-
-  oldtail = list->tail;
-  if (oldtail)
-    oldtail->next = node;
-  list->tail = node;
-  if (!list->head)
-    list->head = node;
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, " -> using data %p", node->data);
-
-  ne_ctx_push(ctx, desc->children, node->data);
-}
-
-static void
-ne_read_single_master(nestegg * ctx, struct ebml_element_desc * desc)
-{
-  assert(desc->type == TYPE_MASTER && !(desc->flags & DESC_FLAG_MULTI));
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "single master element %llx (%s)",
-           desc->id, desc->name);
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, " -> using data %p (%u)",
-           ctx->ancestor->data + desc->offset, desc->offset);
-
-  ne_ctx_push(ctx, desc->children, ctx->ancestor->data + desc->offset);
-}
-
-static int
-ne_read_simple(nestegg * ctx, struct ebml_element_desc * desc, size_t length)
-{
-  struct ebml_type * storage;
-  int r = 0;
-
-  storage = (struct ebml_type *) (ctx->ancestor->data + desc->offset);
-
-  if (storage->read) {
-    ctx->log(ctx, NESTEGG_LOG_DEBUG, "element %llx (%s) already read, skipping",
-             desc->id, desc->name);
-    return 0;
-  }
-
-  storage->type = desc->type;
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "element %llx (%s) -> %p (%u)",
-           desc->id, desc->name, storage, desc->offset);
-
-  switch (desc->type) {
-  case TYPE_UINT:
-    r = ne_read_uint(ctx->io, &storage->v.u, length);
-    break;
-  case TYPE_FLOAT:
-    r = ne_read_float(ctx->io, &storage->v.f, length);
-    break;
-  case TYPE_INT:
-    r = ne_read_int(ctx->io, &storage->v.i, length);
-    break;
-  case TYPE_STRING:
-    r = ne_read_string(ctx, &storage->v.s, length);
-    break;
-  case TYPE_BINARY:
-    r = ne_read_binary(ctx, &storage->v.b, length);
-    break;
-  case TYPE_MASTER:
-  case TYPE_UNKNOWN:
-    assert(0);
-    break;
-  }
-
-  if (r == 1)
-    storage->read = 1;
-
-  return r;
-}
-
-static int
-ne_parse(nestegg * ctx, struct ebml_element_desc * top_level, int64_t max_offset)
-{
-  int r;
-  int64_t * data_offset;
-  uint64_t id, size, peeked_id;
-  struct ebml_element_desc * element;
-
-  if (!ctx->ancestor)
-    return -1;
-
-  for (;;) {
-    if (max_offset > 0 && ne_io_tell(ctx->io) >= max_offset) {
-      /* Reached end of offset allowed for parsing - return gracefully */
-      r = 1;
-      break;
-    }
-    r = ne_peek_element(ctx, &id, &size);
-    if (r != 1)
-      break;
-    peeked_id = id;
-
-    element = ne_find_element(id, ctx->ancestor->node);
-    if (element) {
-      if (element->flags & DESC_FLAG_SUSPEND) {
-        assert(element->type == TYPE_BINARY);
-        ctx->log(ctx, NESTEGG_LOG_DEBUG, "suspend parse at %llx", id);
-        r = 1;
-        break;
-      }
-
-      r = ne_read_element(ctx, &id, &size);
-      if (r != 1)
-        break;
-      assert(id == peeked_id);
-
-      if (element->flags & DESC_FLAG_OFFSET) {
-        data_offset = (int64_t *) (ctx->ancestor->data + element->data_offset);
-        *data_offset = ne_io_tell(ctx->io);
-        if (*data_offset < 0) {
-          r = -1;
-          break;
-        }
-      }
-
-      if (element->type == TYPE_MASTER) {
-        if (element->flags & DESC_FLAG_MULTI)
-          ne_read_master(ctx, element);
-        else
-          ne_read_single_master(ctx, element);
-        continue;
-      } else {
-        r = ne_read_simple(ctx, element, (size_t)size);
-        if (r < 0)
-          break;
-      }
-    } else if (ne_is_ancestor_element(id, ctx->ancestor->previous)) {
-      ctx->log(ctx, NESTEGG_LOG_DEBUG, "parent element %llx", id);
-      if (top_level && ctx->ancestor->node == top_level) {
-        ctx->log(ctx, NESTEGG_LOG_DEBUG, "*** parse about to back up past top_level");
-        r = 1;
-        break;
-      }
-      ne_ctx_pop(ctx);
-    } else {
-      r = ne_read_element(ctx, &id, &size);
-      if (r != 1)
-        break;
-
-      if (id != ID_VOID && id != ID_CRC32)
-        ctx->log(ctx, NESTEGG_LOG_DEBUG, "unknown element %llx", id);
-      r = ne_io_read_skip(ctx->io, (size_t)size);
-      if (r != 1)
-        break;
-    }
-  }
-
-  if (r != 1)
-    while (ctx->ancestor)
-      ne_ctx_pop(ctx);
-
-  return r;
-}
-
-static uint64_t
-ne_xiph_lace_value(unsigned char ** np)
-{
-  uint64_t lace;
-  uint64_t value;
-  unsigned char * p = *np;
-
-  lace = *p++;
-  value = lace;
-  while (lace == 255) {
-    lace = *p++;
-    value += lace;
-  }
-
-  *np = p;
-
-  return value;
-}
-
-static int
-ne_read_xiph_lace_value(nestegg_io * io, uint64_t * value, size_t * consumed)
-{
-  int r;
-  uint64_t lace;
-
-  r = ne_read_uint(io, &lace, 1);
-  if (r != 1)
-    return r;
-  *consumed += 1;
-
-  *value = lace;
-  while (lace == 255) {
-    r = ne_read_uint(io, &lace, 1);
-    if (r != 1)
-      return r;
-    *consumed += 1;
-    *value += lace;
-  }
-
-  return 1;
-}
-
-static int
-ne_read_xiph_lacing(nestegg_io * io, size_t block, size_t * read, uint64_t n, uint64_t * sizes)
-{
-  int r;
-  size_t i = 0;
-  uint64_t sum = 0;
-
-  while (--n) {
-    r = ne_read_xiph_lace_value(io, &sizes[i], read);
-    if (r != 1)
-      return r;
-    sum += sizes[i];
-    i += 1;
-  }
-
-  if (*read + sum > block)
-    return -1;
-
-  /* Last frame is the remainder of the block. */
-  sizes[i] = block - *read - sum;
-  return 1;
-}
-
-static int
-ne_read_ebml_lacing(nestegg_io * io, size_t block, size_t * read, uint64_t n, uint64_t * sizes)
-{
-  int r;
-  uint64_t lace, sum, length;
-  int64_t slace;
-  size_t i = 0;
-
-  r = ne_read_vint(io, &lace, &length);
-  if (r != 1)
-    return r;
-  assert(length <= 8);
-  *read += (size_t)length;
-
-  sizes[i] = lace;
-  sum = sizes[i];
-
-  i += 1;
-  n -= 1;
-
-  while (--n) {
-    r = ne_read_svint(io, &slace, &length);
-    if (r != 1)
-      return r;
-    assert(length <= 8);
-    *read += (size_t)length;
-    sizes[i] = sizes[i - 1] + slace;
-    sum += sizes[i];
-    i += 1;
-  }
-
-  if (*read + sum > block)
-    return -1;
-
-  /* Last frame is the remainder of the block. */
-  sizes[i] = block - *read - sum;
-  return 1;
-}
-
-static uint64_t
-ne_get_timecode_scale(nestegg * ctx)
-{
-  uint64_t scale;
-
-  if (ne_get_uint(ctx->segment.info.timecode_scale, &scale) != 0)
-    scale = 1000000;
-
-  return scale;
-}
-
-static int
-ne_map_track_number_to_index(nestegg * ctx,
-                             unsigned int track_number,
-                             unsigned int * track_index)
-{
-  struct ebml_list_node * node;
-  struct track_entry * t_entry;
-  uint64_t t_number = 0;
-
-  if (!track_index)
-    return -1;
-  *track_index = 0;
-
-  if (track_number == 0)
-    return -1;
-
-  node = ctx->segment.tracks.track_entry.head;
-  while (node) {
-    assert(node->id == ID_TRACK_ENTRY);
-    t_entry = node->data;
-    if (ne_get_uint(t_entry->number, &t_number) != 0)
-      return -1;
-    if (t_number == track_number)
-      return 0;
-    *track_index += 1;
-    node = node->next;
-  }
-
-  return -1;
-}
-
-static struct track_entry *
-ne_find_track_entry(nestegg * ctx, unsigned int track)
-{
-  struct ebml_list_node * node;
-  unsigned int tracks = 0;
-
-  node = ctx->segment.tracks.track_entry.head;
-  while (node) {
-    assert(node->id == ID_TRACK_ENTRY);
-    if (track == tracks)
-      return node->data;
-    tracks += 1;
-    node = node->next;
-  }
-
-  return NULL;
-}
-
-static int
-ne_read_block(nestegg * ctx, uint64_t block_id, uint64_t block_size, nestegg_packet ** data)
-{
-  int r;
-  int64_t timecode, abs_timecode;
-  nestegg_packet * pkt;
-  struct cluster * cluster;
-  struct frame * f, * last;
-  struct track_entry * entry;
-  const int track_scale = 1;
-  uint64_t track_number, length, frame_sizes[256], cluster_tc, flags, frames, tc_scale, total;
-  unsigned int i, lacing, track;
-  size_t consumed = 0;
-
-  *data = NULL;
-
-  if (block_size > LIMIT_BLOCK)
-    return -1;
-
-  r = ne_read_vint(ctx->io, &track_number, &length);
-  if (r != 1)
-    return r;
-
-  if (track_number == 0 || (unsigned int)track_number != track_number)
-    return -1;
-
-  assert(length <= 8);
-  consumed += (size_t)length;
-
-  r = ne_read_int(ctx->io, &timecode, 2);
-  if (r != 1)
-    return r;
-
-  consumed += 2;
-
-  r = ne_read_uint(ctx->io, &flags, 1);
-  if (r != 1)
-    return r;
-
-  consumed += 1;
-
-  frames = 0;
-
-  /* Flags are different between Block and SimpleBlock, but lacing is
-     encoded the same way. */
-  lacing = (flags & BLOCK_FLAGS_LACING) >> 1;
-
-  switch (lacing) {
-  case LACING_NONE:
-    frames = 1;
-    break;
-  case LACING_XIPH:
-  case LACING_FIXED:
-  case LACING_EBML:
-    r = ne_read_uint(ctx->io, &frames, 1);
-    if (r != 1)
-      return r;
-    consumed += 1;
-    frames += 1;
-  }
-
-  if (frames > 256)
-    return -1;
-
-  switch (lacing) {
-  case LACING_NONE:
-    frame_sizes[0] = block_size - consumed;
-    break;
-  case LACING_XIPH:
-    if (frames == 1)
-      return -1;
-    r = ne_read_xiph_lacing(ctx->io, (size_t)block_size, &consumed, frames, frame_sizes);
-    if (r != 1)
-      return r;
-    break;
-  case LACING_FIXED:
-    if ((block_size - consumed) % frames)
-      return -1;
-    for (i = 0; i < frames; ++i)
-      frame_sizes[i] = (block_size - consumed) / frames;
-    break;
-  case LACING_EBML:
-    if (frames == 1)
-      return -1;
-    r = ne_read_ebml_lacing(ctx->io, (size_t)block_size, &consumed, frames, frame_sizes);
-    if (r != 1)
-      return r;
-    break;
-  }
-
-  /* Sanity check unlaced frame sizes against total block size. */
-  total = consumed;
-  for (i = 0; i < frames; ++i)
-    total += frame_sizes[i];
-  if (total > block_size)
-    return -1;
-
-  if (ne_map_track_number_to_index(ctx, (unsigned int)track_number, &track) != 0)
-    return -1;
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  tc_scale = ne_get_timecode_scale(ctx);
-
-  assert(ctx->segment.cluster.tail->id == ID_CLUSTER);
-  cluster = ctx->segment.cluster.tail->data;
-  if (ne_get_uint(cluster->timecode, &cluster_tc) != 0)
-    return -1;
-
-  abs_timecode = timecode + cluster_tc;
-  if (abs_timecode < 0)
-    return -1;
-
-  pkt = ne_alloc(sizeof(*pkt));
-  pkt->track = track;
-  pkt->timecode = abs_timecode * tc_scale * track_scale;
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "%sblock t %lld pts %f f %llx frames: %llu",
-           block_id == ID_BLOCK ? "" : "simple", pkt->track, pkt->timecode / 1e9, flags, frames);
-
-  last = NULL;
-  for (i = 0; i < frames; ++i) {
-    if (frame_sizes[i] > LIMIT_FRAME) {
-      nestegg_free_packet(pkt);
-      return -1;
-    }
-    f = ne_alloc(sizeof(*f));
-    f->length = (size_t)frame_sizes[i];
-    f->data = ne_alloc(f->length);
-    r = ne_io_read(ctx->io, f->data, f->length);
-    if (r != 1) {
-      free(f->data);
-      free(f);
-      nestegg_free_packet(pkt);
-      return -1;
-    }
-
-    if (!last)
-      pkt->frame = f;
-    else
-      last->next = f;
-    last = f;
-  }
-
-  *data = pkt;
-
-  return 1;
-}
-
-static int
-ne_read_discard_padding(nestegg * ctx, nestegg_packet * pkt)
-{
-  int r;
-  uint64_t id, size;
-  struct ebml_element_desc * element;
-  struct ebml_type * storage;
-
-  r = ne_peek_element(ctx, &id, &size);
-  if (r != 1)
-    return r;
-
-  if (id != ID_DISCARD_PADDING)
-    return 1;
-
-  element = ne_find_element(id, ctx->ancestor->node);
-  if (!element)
-    return 1;
-
-  assert((size_t)size == size);
-  r = ne_read_simple(ctx, element, (size_t)size);
-  if (r != 1)
-    return r;
-  storage = (struct ebml_type *) (ctx->ancestor->data + element->offset);
-  pkt->discard_padding = storage->v.i;
-
-  return 1;
-}
-
-
-static uint64_t
-ne_buf_read_id(unsigned char const * p, size_t length)
-{
-  uint64_t id = 0;
-
-  while (length--) {
-    id <<= 8;
-    id |= *p++;
-  }
-
-  return id;
-}
-
-static struct seek *
-ne_find_seek_for_id(struct ebml_list_node * seek_head, uint64_t id)
-{
-  struct ebml_list * head;
-  struct ebml_list_node * seek;
-  struct ebml_binary binary_id;
-  struct seek * s;
-
-  while (seek_head) {
-    assert(seek_head->id == ID_SEEK_HEAD);
-    head = seek_head->data;
-    seek = head->head;
-
-    while (seek) {
-      assert(seek->id == ID_SEEK);
-      s = seek->data;
-
-      if (ne_get_binary(s->id, &binary_id) == 0 &&
-          ne_buf_read_id(binary_id.data, binary_id.length) == id)
-        return s;
-
-      seek = seek->next;
-    }
-
-    seek_head = seek_head->next;
-  }
-
-  return NULL;
-}
-
-static struct cue_track_positions *
-ne_find_cue_position_for_track(nestegg * ctx, struct ebml_list_node * node, unsigned int track)
-{
-  struct cue_track_positions * pos = NULL;
-  unsigned int track_number;
-  unsigned int t;
-
-  while (node) {
-    assert(node->id == ID_CUE_TRACK_POSITIONS);
-    pos = node->data;
-    if (ne_get_uint32(pos->track, &track_number) != 0)
-      return NULL;
-
-    if (ne_map_track_number_to_index(ctx, track_number, &t) != 0)
-      return NULL;
-
-    if (t == track)
-      return pos;
-
-    node = node->next;
-  }
-
-  return NULL;
-}
-
-static struct cue_point *
-ne_find_cue_point_for_tstamp(nestegg * ctx, struct ebml_list_node * cue_point, unsigned int track, uint64_t scale, uint64_t tstamp)
-{
-  uint64_t time;
-  struct cue_point * c, * prev = NULL;
-
-  while (cue_point) {
-    assert(cue_point->id == ID_CUE_POINT);
-    c = cue_point->data;
-
-    if (!prev)
-      prev = c;
-
-    if (ne_get_uint(c->time, &time) == 0 && time * scale > tstamp)
-      break;
-
-    if (ne_find_cue_position_for_track(ctx, c->cue_track_positions.head, track) != NULL)
-      prev = c;
-
-    cue_point = cue_point->next;
-  }
-
-  return prev;
-}
-
-static int
-ne_is_suspend_element(uint64_t id)
-{
-  if (id == ID_SIMPLE_BLOCK || id == ID_BLOCK)
-    return 1;
-  return 0;
-}
-
-static void
-ne_null_log_callback(nestegg * ctx, unsigned int severity, char const * fmt, ...)
-{
-  if (ctx && severity && fmt)
-    return;
-}
-
-static int
-ne_init_cue_points(nestegg * ctx, int64_t max_offset)
-{
-  int r;
-  struct ebml_list_node * node = ctx->segment.cues.cue_point.head;
-  struct seek * found;
-  uint64_t seek_pos, id;
-  struct saved_state state;
-
-  /* If there are no cues loaded, check for cues element in the seek head
-     and load it. */
-  if (!node) {
-    found = ne_find_seek_for_id(ctx->segment.seek_head.head, ID_CUES);
-    if (!found)
-      return -1;
-
-    if (ne_get_uint(found->position, &seek_pos) != 0)
-      return -1;
-
-    /* Save old parser state. */
-    r = ne_ctx_save(ctx, &state);
-    if (r != 0)
-      return -1;
-
-    /* Seek and set up parser state for segment-level element (Cues). */
-    r = ne_io_seek(ctx->io, ctx->segment_offset + seek_pos, NESTEGG_SEEK_SET);
-    if (r != 0)
-      return -1;
-    ctx->last_valid = 0;
-
-    r = ne_read_element(ctx, &id, NULL);
-    if (r != 1)
-      return -1;
-
-    if (id != ID_CUES)
-      return -1;
-
-    ctx->ancestor = NULL;
-    ne_ctx_push(ctx, ne_top_level_elements, ctx);
-    ne_ctx_push(ctx, ne_segment_elements, &ctx->segment);
-    ne_ctx_push(ctx, ne_cues_elements, &ctx->segment.cues);
-    /* parser will run until end of cues element. */
-    ctx->log(ctx, NESTEGG_LOG_DEBUG, "seek: parsing cue elements");
-    r = ne_parse(ctx, ne_cues_elements, max_offset);
-    while (ctx->ancestor)
-      ne_ctx_pop(ctx);
-
-    /* Reset parser state to original state and seek back to old position. */
-    if (ne_ctx_restore(ctx, &state) != 0)
-      return -1;
-
-    if (r < 0)
-      return -1;
-
-    node = ctx->segment.cues.cue_point.head;
-    if (!node)
-      return -1;
-  }
-
-  return 0;
-}
-
-/* Three functions that implement the nestegg_io interface, operating on a
- * sniff_buffer. */
-struct sniff_buffer {
-  unsigned char const * buffer;
-  size_t length;
-  int64_t offset;
-};
-
-static int
-ne_buffer_read(void * buffer, size_t length, void * user_data)
-{
-  struct sniff_buffer * sb = user_data;
-
-  int rv = 1;
-  size_t available = sb->length - (size_t)sb->offset;
-
-  if (available < length)
-    return 0;
-
-  memcpy(buffer, sb->buffer + sb->offset, length);
-  sb->offset += length;
-
-  return rv;
-}
-
-static int
-ne_buffer_seek(int64_t offset, int whence, void * user_data)
-{
-  struct sniff_buffer * sb = user_data;
-  int64_t o = sb->offset;
-
-  switch(whence) {
-    case NESTEGG_SEEK_SET:
-      o = offset;
-      break;
-    case NESTEGG_SEEK_CUR:
-      o += offset;
-      break;
-    case NESTEGG_SEEK_END:
-      o = sb->length + offset;
-      break;
-  }
-
-  if (o < 0 || o > (int64_t) sb->length)
-    return -1;
-
-  sb->offset = o;
-  return 0;
-}
-
-static int64_t
-ne_buffer_tell(void * user_data)
-{
-  struct sniff_buffer * sb = user_data;
-  return sb->offset;
-}
-
-static int
-ne_match_webm(nestegg_io io, int64_t max_offset)
-{
-  int r;
-  uint64_t id;
-  char * doctype;
-  nestegg * ctx;
-
-  if (!(io.read && io.seek && io.tell))
-    return -1;
-
-  ctx = ne_alloc(sizeof(*ctx));
-
-  ctx->io = ne_alloc(sizeof(*ctx->io));
-  *ctx->io = io;
-  ctx->alloc_pool = ne_pool_init();
-  ctx->log = ne_null_log_callback;
-
-  r = ne_peek_element(ctx, &id, NULL);
-  if (r != 1) {
-    nestegg_destroy(ctx);
-    return 0;
-  }
-
-  if (id != ID_EBML) {
-    nestegg_destroy(ctx);
-    return 0;
-  }
-
-  ne_ctx_push(ctx, ne_top_level_elements, ctx);
-
-  /* we don't check the return value of ne_parse, that might fail because
-   * max_offset is not on a valid element end point. We only want to check
-   * the EBML ID and that the doctype is "webm". */
-  ne_parse(ctx, NULL, max_offset);
-
-  if (ne_get_string(ctx->ebml.doctype, &doctype) != 0 ||
-      strcmp(doctype, "webm") != 0) {
-    nestegg_destroy(ctx);
-    return 0;
-  }
-
-  nestegg_destroy(ctx);
-
-  return 1;
-}
-
-int
-nestegg_init(nestegg ** context, nestegg_io io, nestegg_log callback, int64_t max_offset)
-{
-  int r;
-  uint64_t id, version, docversion;
-  struct ebml_list_node * track;
-  char * doctype;
-  nestegg * ctx;
-
-  if (!(io.read && io.seek && io.tell))
-    return -1;
-
-  ctx = ne_alloc(sizeof(*ctx));
-
-  ctx->io = ne_alloc(sizeof(*ctx->io));
-  *ctx->io = io;
-  ctx->log = callback;
-  ctx->alloc_pool = ne_pool_init();
-
-  if (!ctx->log)
-    ctx->log = ne_null_log_callback;
-
-  r = ne_peek_element(ctx, &id, NULL);
-  if (r != 1) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  if (id != ID_EBML) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "ctx %p", ctx);
-
-  ne_ctx_push(ctx, ne_top_level_elements, ctx);
-
-  r = ne_parse(ctx, NULL, max_offset);
-
-  if (r != 1) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  if (ne_get_uint(ctx->ebml.ebml_read_version, &version) != 0)
-    version = 1;
-  if (version != 1) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  if (ne_get_string(ctx->ebml.doctype, &doctype) != 0)
-    doctype = "matroska";
-  if (strcmp(doctype, "webm") != 0) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  if (ne_get_uint(ctx->ebml.doctype_read_version, &docversion) != 0)
-    docversion = 1;
-  if (docversion < 1 || docversion > 2) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  if (!ctx->segment.tracks.track_entry.head) {
-    nestegg_destroy(ctx);
-    return -1;
-  }
-
-  track = ctx->segment.tracks.track_entry.head;
-  ctx->track_count = 0;
-
-  while (track) {
-    ctx->track_count += 1;
-    track = track->next;
-  }
-
-  *context = ctx;
-
-  return 0;
-}
-
-void
-nestegg_destroy(nestegg * ctx)
-{
-  while (ctx->ancestor)
-    ne_ctx_pop(ctx);
-  ne_pool_destroy(ctx->alloc_pool);
-  free(ctx->io);
-  free(ctx);
-}
-
-int
-nestegg_duration(nestegg * ctx, uint64_t * duration)
-{
-  uint64_t tc_scale;
-  double unscaled_duration;
-
-  if (ne_get_float(ctx->segment.info.duration, &unscaled_duration) != 0)
-    return -1;
-
-  tc_scale = ne_get_timecode_scale(ctx);
-
-  *duration = (uint64_t) (unscaled_duration * tc_scale);
-  return 0;
-}
-
-int
-nestegg_tstamp_scale(nestegg * ctx, uint64_t * scale)
-{
-  *scale = ne_get_timecode_scale(ctx);
-  return 0;
-}
-
-int
-nestegg_track_count(nestegg * ctx, unsigned int * tracks)
-{
-  *tracks = ctx->track_count;
-  return 0;
-}
-
-int
-nestegg_get_cue_point(nestegg * ctx, unsigned int cluster_num, int64_t max_offset,
-                      int64_t * start_pos, int64_t * end_pos, uint64_t * tstamp)
-{
-  int range_obtained = 0;
-  unsigned int cluster_count = 0;
-  struct cue_point * cue_point;
-  struct cue_track_positions * pos;
-  uint64_t seek_pos, track_number, tc_scale, time;
-  struct ebml_list_node * cues_node = ctx->segment.cues.cue_point.head;
-  struct ebml_list_node * cue_pos_node = NULL;
-  unsigned int track = 0, track_count = 0, track_index;
-
-  if (!start_pos || !end_pos || !tstamp)
-    return -1;
-
-  /* Initialise return values */
-  *start_pos = -1;
-  *end_pos = -1;
-  *tstamp = 0;
-
-  if (!cues_node) {
-    ne_init_cue_points(ctx, max_offset);
-    cues_node = ctx->segment.cues.cue_point.head;
-    /* Verify cues have been added to context. */
-    if (!cues_node)
-      return -1;
-  }
-
-  nestegg_track_count(ctx, &track_count);
-
-  tc_scale = ne_get_timecode_scale(ctx);
-
-  while (cues_node && !range_obtained) {
-    assert(cues_node->id == ID_CUE_POINT);
-    cue_point = cues_node->data;
-    cue_pos_node = cue_point->cue_track_positions.head;
-    while (cue_pos_node) {
-      assert(cue_pos_node->id == ID_CUE_TRACK_POSITIONS);
-      pos = cue_pos_node->data;
-      for (track = 0; track < track_count; track++) {
-        if (ne_get_uint(pos->track, &track_number) != 0)
-          return -1;
-
-        if (ne_map_track_number_to_index(ctx, (unsigned int)track_number, &track_index) != 0)
-          return -1;
-
-        if (track_index == track) {
-          if (ne_get_uint(pos->cluster_position, &seek_pos) != 0)
-            return -1;
-          if (cluster_count == cluster_num) {
-            *start_pos = ctx->segment_offset+seek_pos;
-            if (ne_get_uint(cue_point->time, &time) != 0)
-              return -1;
-            *tstamp = time * tc_scale;
-          } else if (cluster_count == cluster_num+1) {
-            *end_pos = (ctx->segment_offset+seek_pos)-1;
-            range_obtained = 1;
-            break;
-          }
-          cluster_count++;
-        }
-      }
-      cue_pos_node = cue_pos_node->next;
-    }
-    cues_node = cues_node->next;
-  }
-
-  return 0;
-}
-
-int
-nestegg_offset_seek(nestegg * ctx, uint64_t offset)
-{
-  int r;
-
-  /* Seek and set up parser state for segment-level element (Cluster). */
-  r = ne_io_seek(ctx->io, offset, NESTEGG_SEEK_SET);
-  if (r != 0)
-    return -1;
-  ctx->last_valid = 0;
-
-  while (ctx->ancestor)
-    ne_ctx_pop(ctx);
-
-  ne_ctx_push(ctx, ne_top_level_elements, ctx);
-  ne_ctx_push(ctx, ne_segment_elements, &ctx->segment);
-
-  return 0;
-}
-
-int
-nestegg_track_seek(nestegg * ctx, unsigned int track, uint64_t tstamp)
-{
-  int r;
-  struct cue_point * cue_point;
-  struct cue_track_positions * pos;
-  uint64_t seek_pos, tc_scale;
-
-  /* If there are no cues loaded, check for cues element in the seek head
-     and load it. */
-  if (!ctx->segment.cues.cue_point.head) {
-    r = ne_init_cue_points(ctx, -1);
-    if (r != 0)
-      return -1;
-  }
-
-  tc_scale = ne_get_timecode_scale(ctx);
-
-  cue_point = ne_find_cue_point_for_tstamp(ctx, ctx->segment.cues.cue_point.head,
-                                           track, tc_scale, tstamp);
-  if (!cue_point)
-    return -1;
-
-  pos = ne_find_cue_position_for_track(ctx, cue_point->cue_track_positions.head, track);
-  if (pos == NULL)
-    return -1;
-
-  if (ne_get_uint(pos->cluster_position, &seek_pos) != 0)
-    return -1;
-
-  /* Seek and set up parser state for segment-level element (Cluster). */
-  r = nestegg_offset_seek(ctx, ctx->segment_offset + seek_pos);
-  ctx->log(ctx, NESTEGG_LOG_DEBUG, "seek: parsing cluster elements");
-  r = ne_parse(ctx, NULL, -1);
-  if (r != 1)
-    return -1;
-
-  if (!ne_is_suspend_element(ctx->last_id))
-    return -1;
-
-  return 0;
-}
-
-int
-nestegg_track_type(nestegg * ctx, unsigned int track)
-{
-  struct track_entry * entry;
-  uint64_t type;
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (ne_get_uint(entry->type, &type) != 0)
-    return -1;
-
-  if (type & TRACK_TYPE_VIDEO)
-    return NESTEGG_TRACK_VIDEO;
-
-  if (type & TRACK_TYPE_AUDIO)
-    return NESTEGG_TRACK_AUDIO;
-
-  return -1;
-}
-
-int
-nestegg_track_codec_id(nestegg * ctx, unsigned int track)
-{
-  char * codec_id;
-  struct track_entry * entry;
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (ne_get_string(entry->codec_id, &codec_id) != 0)
-    return -1;
-
-  if (strcmp(codec_id, TRACK_ID_VP8) == 0)
-    return NESTEGG_CODEC_VP8;
-
-  if (strcmp(codec_id, TRACK_ID_VP9) == 0)
-    return NESTEGG_CODEC_VP9;
-
-  if (strcmp(codec_id, TRACK_ID_VORBIS) == 0)
-    return NESTEGG_CODEC_VORBIS;
-
-  if (strcmp(codec_id, TRACK_ID_OPUS) == 0)
-    return NESTEGG_CODEC_OPUS;
-
-  return -1;
-}
-
-int
-nestegg_track_codec_data_count(nestegg * ctx, unsigned int track,
-                               unsigned int * count)
-{
-  struct track_entry * entry;
-  struct ebml_binary codec_private;
-  unsigned char * p;
-
-  *count = 0;
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (nestegg_track_codec_id(ctx, track) != NESTEGG_CODEC_VORBIS)
-    return -1;
-
-  if (ne_get_binary(entry->codec_private, &codec_private) != 0)
-    return -1;
-
-  if (codec_private.length < 1)
-    return -1;
-
-  p = codec_private.data;
-  *count = *p + 1;
-
-  if (*count > 3)
-    return -1;
-
-  return 0;
-}
-
-int
-nestegg_track_codec_data(nestegg * ctx, unsigned int track, unsigned int item,
-                         unsigned char ** data, size_t * length)
-{
-  struct track_entry * entry;
-  struct ebml_binary codec_private;
-  uint64_t sizes[3], total;
-  unsigned char * p;
-  unsigned int count, i;
-
-  *data = NULL;
-  *length = 0;
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (nestegg_track_codec_id(ctx, track) != NESTEGG_CODEC_VORBIS
-    && nestegg_track_codec_id(ctx, track) != NESTEGG_CODEC_OPUS)
-    return -1;
-
-  if (ne_get_binary(entry->codec_private, &codec_private) != 0)
-    return -1;
-
-  if (nestegg_track_codec_id(ctx, track) == NESTEGG_CODEC_VORBIS) {
-      p = codec_private.data;
-      count = *p++ + 1;
-
-      if (count > 3)
-        return -1;
-
-      i = 0;
-      total = 0;
-      while (--count) {
-        sizes[i] = ne_xiph_lace_value(&p);
-        total += sizes[i];
-        i += 1;
-      }
-      sizes[i] = codec_private.length - total - (p - codec_private.data);
-
-      for (i = 0; i < item; ++i) {
-        if (sizes[i] > LIMIT_FRAME)
-          return -1;
-        p += sizes[i];
-      }
-      *data = p;
-      *length = (size_t)sizes[item];
-  } else {
-    *data = codec_private.data;
-    *length = codec_private.length;
-  }
-
-  return 0;
-}
-
-int
-nestegg_track_video_params(nestegg * ctx, unsigned int track,
-                           nestegg_video_params * params)
-{
-  struct track_entry * entry;
-  unsigned int value;
-
-  memset(params, 0, sizeof(*params));
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (nestegg_track_type(ctx, track) != NESTEGG_TRACK_VIDEO)
-    return -1;
-
-  value = 0;
-  ne_get_uint32(entry->video.stereo_mode, &value);
-  if (value <= NESTEGG_VIDEO_STEREO_TOP_BOTTOM ||
-      value == NESTEGG_VIDEO_STEREO_RIGHT_LEFT)
-    params->stereo_mode = value;
-
-  if (ne_get_uint32(entry->video.pixel_width, &value) != 0)
-    return -1;
-  params->width = value;
-
-  if (ne_get_uint32(entry->video.pixel_height, &value) != 0)
-    return -1;
-  params->height = value;
-
-  value = 0;
-  ne_get_uint32(entry->video.pixel_crop_bottom, &value);
-  params->crop_bottom = value;
-
-  value = 0;
-  ne_get_uint32(entry->video.pixel_crop_top, &value);
-  params->crop_top = value;
-
-  value = 0;
-  ne_get_uint32(entry->video.pixel_crop_left, &value);
-  params->crop_left = value;
-
-  value = 0;
-  ne_get_uint32(entry->video.pixel_crop_right, &value);
-  params->crop_right = value;
-
-  value = params->width;
-  ne_get_uint32(entry->video.display_width, &value);
-  params->display_width = value;
-
-  value = params->height;
-  ne_get_uint32(entry->video.display_height, &value);
-  params->display_height = value;
-
-  return 0;
-}
-
-int
-nestegg_track_audio_params(nestegg * ctx, unsigned int track,
-                           nestegg_audio_params * params)
-{
-  struct track_entry * entry;
-  unsigned int value;
-
-  memset(params, 0, sizeof(*params));
-
-  entry = ne_find_track_entry(ctx, track);
-  if (!entry)
-    return -1;
-
-  if (nestegg_track_type(ctx, track) != NESTEGG_TRACK_AUDIO)
-    return -1;
-
-  params->rate = 8000;
-  ne_get_float(entry->audio.sampling_frequency, &params->rate);
-
-  value = 1;
-  ne_get_uint32(entry->audio.channels, &value);
-  params->channels = value;
-
-  value = 16;
-  ne_get_uint32(entry->audio.bit_depth, &value);
-  params->depth = value;
-
-  value = 0;
-  ne_get_uint32(entry->codec_delay, &value);
-  params->codec_delay = value;
-
-  value = 0;
-  ne_get_uint32(entry->seek_preroll, &value);
-  params->seek_preroll = value;
-
-  return 0;
-}
-
-int
-nestegg_read_packet(nestegg * ctx, nestegg_packet ** pkt)
-{
-  int r;
-  uint64_t id, size;
-
-  *pkt = NULL;
-
-  for (;;) {
-    r = ne_peek_element(ctx, &id, &size);
-    if (r != 1)
-      return r;
-
-    /* Any DESC_FLAG_SUSPEND fields must be handled here. */
-    if (ne_is_suspend_element(id)) {
-      r = ne_read_element(ctx, &id, &size);
-      if (r != 1)
-        return r;
-
-      /* The only DESC_FLAG_SUSPEND fields are Blocks and SimpleBlocks, which we
-         handle directly. */
-      r = ne_read_block(ctx, id, size, pkt);
-      if (r != 1)
-        return r;
-
-      r = ne_read_discard_padding(ctx, *pkt);
-      if (r != 1)
-        return r;
-
-      return r;
-    }
-
-    r =  ne_parse(ctx, NULL, -1);
-    if (r != 1)
-      return r;
-  }
-
-  return 1;
-}
-
-void
-nestegg_free_packet(nestegg_packet * pkt)
-{
-  struct frame * frame;
-
-  while (pkt->frame) {
-    frame = pkt->frame;
-    pkt->frame = frame->next;
-    free(frame->data);
-    free(frame);
-  }
-
- free(pkt);
-}
-
-int
-nestegg_packet_track(nestegg_packet * pkt, unsigned int * track)
-{
-  *track = (unsigned int)pkt->track;
-  return 0;
-}
-
-int
-nestegg_packet_tstamp(nestegg_packet * pkt, uint64_t * tstamp)
-{
-  *tstamp = pkt->timecode;
-  return 0;
-}
-
-int
-nestegg_packet_discard_padding(nestegg_packet * pkt, int64_t * discard_padding)
-{
-  *discard_padding = pkt->discard_padding;
-  return 0;
-}
-
-int
-nestegg_packet_count(nestegg_packet * pkt, unsigned int * count)
-{
-  struct frame * f = pkt->frame;
-
-  *count = 0;
-
-  while (f) {
-    *count += 1;
-    f = f->next;
-  }
-
-  return 0;
-}
-
-int
-nestegg_packet_data(nestegg_packet * pkt, unsigned int item,
-                    unsigned char ** data, size_t * length)
-{
-  struct frame * f = pkt->frame;
-  unsigned int count = 0;
-
-  *data = NULL;
-  *length = 0;
-
-  while (f) {
-    if (count == item) {
-      *data = f->data;
-      *length = f->length;
-      return 0;
-    }
-    count += 1;
-    f = f->next;
-  }
-
-  return -1;
-}
-
-int
-nestegg_has_cues(nestegg * ctx)
-{
-  return ctx->segment.cues.cue_point.head ||
-         ne_find_seek_for_id(ctx->segment.seek_head.head, ID_CUES);
-}
-
-int
-nestegg_sniff(unsigned char const * buffer, size_t length)
-{
-  nestegg_io io;
-  struct sniff_buffer user_data;
-
-  user_data.buffer = buffer;
-  user_data.length = length;
-  user_data.offset = 0;
-
-  io.read = ne_buffer_read;
-  io.seek = ne_buffer_seek;
-  io.tell = ne_buffer_tell;
-  io.userdata = &user_data;
-  return ne_match_webm(io, length);
-}
-