Adding VP8 Alpha support in Media Source

media/webm/webm_cluster_parser.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/webm/webm_cluster_parser.h"
 
 #include <vector>
 
 #include "base/logging.h"
+#include "base/sys_byteorder.h"
 #include "media/base/buffers.h"
 #include "media/base/decrypt_config.h"
 #include "media/webm/webm_constants.h"
 #include "media/webm/webm_crypto_helpers.h"
 
 namespace media {
 
 WebMClusterParser::TextTrackIterator::TextTrackIterator(
     const TextTrackMap& text_track_map) :
     iterator_(text_track_map.begin()),
@@ skipping 34 matching lines @@
     const std::string& video_encryption_key_id,
     const LogCB& log_cb)
     : timecode_multiplier_(timecode_scale / 1000.0),
       ignored_tracks_(ignored_tracks),
       audio_encryption_key_id_(audio_encryption_key_id),
       video_encryption_key_id_(video_encryption_key_id),
       parser_(kWebMIdCluster, this),
       last_block_timecode_(-1),
       block_data_size_(-1),
       block_duration_(-1),
+      block_add_id_(-1),
+      block_additional_data_size_(-1),
       cluster_timecode_(-1),
       cluster_start_time_(kNoTimestamp()),
       cluster_ended_(false),
       audio_(audio_track_num, false),
       video_(video_track_num, true),
       log_cb_(log_cb) {
   for (WebMTracksParser::TextTracks::const_iterator it = text_tracks.begin();
        it != text_tracks.end();
        ++it) {
     text_track_map_.insert(std::make_pair(it->first, Track(it->first, false)));
@@ skipping 53 matching lines @@
 }
 
 WebMParserClient* WebMClusterParser::OnListStart(int id) {
   if (id == kWebMIdCluster) {
     cluster_timecode_ = -1;
     cluster_start_time_ = kNoTimestamp();
   } else if (id == kWebMIdBlockGroup) {
     block_data_.reset();
     block_data_size_ = -1;
     block_duration_ = -1;
+  } else if (id == kWebMIdBlockAdditions) {
+    block_add_id_ = -1;
+    block_additional_data_.reset();
+    block_additional_data_size_ = -1;
   }
 
   return this;
 }
 
 bool WebMClusterParser::OnListEnd(int id) {
   if (id != kWebMIdBlockGroup)
     return true;
 
   // Make sure the BlockGroup actually had a Block.
   if (block_data_size_ == -1) {
     MEDIA_LOG(log_cb_) << "Block missing from BlockGroup.";
     return false;
   }
 
   bool result = ParseBlock(false, block_data_.get(), block_data_size_,
-                           block_duration_);
+                           block_additional_data_.get(),
+                           block_additional_data_size_, block_duration_);
   block_data_.reset();
   block_data_size_ = -1;
   block_duration_ = -1;
+  block_add_id_ = -1;
+  block_additional_data_.reset();
+  block_additional_data_size_ = -1;
   return result;
 }
 
 bool WebMClusterParser::OnUInt(int id, int64 val) {
-  if (id == kWebMIdTimecode) {
-    if (cluster_timecode_ != -1)
-      return false;
-
-    cluster_timecode_ = val;
-  } else if (id == kWebMIdBlockDuration) {
-    if (block_duration_ != -1)
-      return false;
-    block_duration_ = val;
+  int64* dst;
+  switch (id) {
+    case kWebMIdTimecode:
+      dst = &cluster_timecode_;
+      break;
+    case kWebMIdBlockDuration:
+      dst = &block_duration_;
+      break;
+    case kWebMIdBlockAddID:
+      dst = &block_add_id_;
+      break;
+    default:
+      return true;
   }
-
+  if (*dst != -1)
+    return false;
+  *dst = val;
   return true;
 }
 
 bool WebMClusterParser::ParseBlock(bool is_simple_block, const uint8* buf,
-                                   int size, int duration) {
+                                   int size, const uint8* additional,
+                                   int additional_size, int duration) {
   if (size < 4)
     return false;
 
   // Return an error if the trackNum > 127. We just aren't
   // going to support large track numbers right now.
   if (!(buf[0] & 0x80)) {
     MEDIA_LOG(log_cb_) << "TrackNumber over 127 not supported";
     return false;
   }
 
   int track_num = buf[0] & 0x7f;
   int timecode = buf[1] << 8 | buf[2];
   int flags = buf[3] & 0xff;
   int lacing = (flags >> 1) & 0x3;
 
   if (lacing) {
     MEDIA_LOG(log_cb_) << "Lacing " << lacing << " is not supported yet.";
     return false;
   }
 
   // Sign extend negative timecode offsets.
   if (timecode & 0x8000)
     timecode |= (-1 << 16);
 
   const uint8* frame_data = buf + 4;
   int frame_size = size - (frame_data - buf);
   return OnBlock(is_simple_block, track_num, timecode, duration, flags,
-                 frame_data, frame_size);
+                 frame_data, frame_size, additional, additional_size);
 }
 
 bool WebMClusterParser::OnBinary(int id, const uint8* data, int size) {
-  if (id == kWebMIdSimpleBlock)
-    return ParseBlock(true, data, size, -1);
+  uint64 block_add_id = base::HostToNet64(block_add_id_);

[acolwell GONE FROM CHROMIUM, 2013/05/21 17:14:11]

Please move this into the case block so that it is closer to the code that
actually uses it.

[vignesh, 2013/05/21 18:57:56]

that's how i had it initially, but the compiler wasn't happy about declaring
variables within case statements (jump to case labels, crosses initialization
error). is there a workaround for this?

+  switch (id) {
+    case kWebMIdSimpleBlock:
+      return ParseBlock(true, data, size, NULL, -1, -1);
 
-  if (id != kWebMIdBlock)
-    return true;
+    case kWebMIdBlock:
+      if (block_data_) {
+        MEDIA_LOG(log_cb_) << "More than 1 Block in a BlockGroup is not "
+                              "supported.";
+        return false;
+      }
+      block_data_.reset(new uint8[size]);
+      memcpy(block_data_.get(), data, size);
+      block_data_size_ = size;
+      return true;
 
-  if (block_data_) {
-    MEDIA_LOG(log_cb_) << "More than 1 Block in a BlockGroup is not supported.";
-    return false;
+    case kWebMIdBlockAdditional:
+      if (block_additional_data_) {
+        // TODO(vigneshv): Technically, more than 1 BlockAdditional is allowed
+        // as per matroska spec. But for now we don't have a use case to
+        // support parsing of such files. Take a look at this again when such a
+        // case arises.
+        MEDIA_LOG(log_cb_) << "More than 1 BlockAdditional in a BlockGroup is "
+                              "not supported.";
+        return false;
+      }
+      // First 8 bytes of side_data in DecoderBuffer is the BlockAddID
+      // element's value in Big Endian format. This is done to mimic ffmpeg
+      // demuxer's behavior.
+      block_additional_data_.reset(new uint8[size + 8]);

[fgalligan1, 2013/05/21 00:02:43]

Make this 8 a constant.

[acolwell GONE FROM CHROMIUM, 2013/05/21 17:14:11]

The constant should probably be initialized with sizeof(block_add_id) instead of
8.

[vignesh, 2013/05/21 18:57:56]

Done.

+      memcpy(block_additional_data_.get(), &block_add_id, 8);
+      memcpy(block_additional_data_.get() + 8, data, size);
+      block_additional_data_size_ = size + 8;

[acolwell GONE FROM CHROMIUM, 2013/05/21 17:14:11]

nit: move this above the block_additional_data_ allocation so that it can be
used in that statement.

[vignesh, 2013/05/21 18:57:56]

Done.

+      return true;
+
+    default:
+      return true;
   }
-
-  block_data_.reset(new uint8[size]);
-  memcpy(block_data_.get(), data, size);
-  block_data_size_ = size;
-  return true;
 }
 
 bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
                                 int timecode,
                                 int  block_duration,
                                 int flags,
-                                const uint8* data, int size) {
+                                const uint8* data, int size,
+                                const uint8* additional, int additional_size) {
   DCHECK_GE(size, 0);
   if (cluster_timecode_ == -1) {
     MEDIA_LOG(log_cb_) << "Got a block before cluster timecode.";
     return false;
   }
 
   if (timecode < 0) {
     MEDIA_LOG(log_cb_) << "Got a block with negative timecode offset "
                        << timecode;
     return false;
@@ skipping 32 matching lines @@
       (cluster_timecode_ + timecode) * timecode_multiplier_);
 
   // The first bit of the flags is set when a SimpleBlock contains only
   // keyframes. If this is a Block, then inspection of the payload is
   // necessary to determine whether it contains a keyframe or not.
   // http://www.matroska.org/technical/specs/index.html
   bool is_keyframe =
       is_simple_block ? (flags & 0x80) != 0 : track->IsKeyframe(data, size);
 
   scoped_refptr<StreamParserBuffer> buffer =
-      StreamParserBuffer::CopyFrom(data, size, is_keyframe);
+      StreamParserBuffer::CopyFrom(data, size, additional, additional_size,
+                                   is_keyframe);
 
   // Every encrypted Block has a signal byte and IV prepended to it. Current
   // encrypted WebM request for comments specification is here
   // http://wiki.webmproject.org/encryption/webm-encryption-rfc
   if (!encryption_key_id.empty()) {
     scoped_ptr<DecryptConfig> config(WebMCreateDecryptConfig(
         data, size,
         reinterpret_cast<const uint8*>(encryption_key_id.data()),
         encryption_key_id.size()));
     if (!config)
@@ skipping 71 matching lines @@
 WebMClusterParser::FindTextTrack(int track_num) {
   const TextTrackMap::iterator it = text_track_map_.find(track_num);
 
   if (it == text_track_map_.end())
     return NULL;
 
   return &it->second;
 }
 
 }  // namespace media