Adding ChunkDemuxer implementation.

media/webm/cluster_builder.cc

+// Copyright (c) 2011 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/cluster_builder.h"
+
+#include "base/logging.h"
+
+namespace media {
+
+static const uint8 kClusterHeader[] = {
+  0x1F, 0x43, 0xB6, 0x75, // CLUSTER ID

[scherkus (not reviewing), 2011/06/28 20:03:29]

two spaces

[acolwell GONE FROM CHROMIUM, 2011/06/29 16:38:43]

Done.

+  0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // cluster(size = 0)
+  0xE7, // Timecode ID
+  0x88, // timecode(size=8)
+  0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // timecode value
+};
+
+const int kClusterHeaderSize = sizeof(kClusterHeader);
+const int kClusterSizeOffset = 4;
+const int kClusterTimecodeOffset = 14;
+
+static const uint8 kSimpleBlockHeader[] = {
+  0xA3, // SimpleBlock ID

[scherkus (not reviewing), 2011/06/28 20:03:29]

two spaces

[acolwell GONE FROM CHROMIUM, 2011/06/29 16:38:43]

Done.

+  0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // SimpleBlock(size = 0)
+};
+
+const int kSimpleBlockHeaderSize = sizeof(kSimpleBlockHeader);
+const int kSimpleBlockSizeOffset = 1;
+
+const int kInitialBufferSize = 32768;
+
+ClusterBuilder::ClusterBuilder(int64 cluster_timecode)
+    : buffer_(new uint8[kInitialBufferSize]),
+      buffer_size_(kInitialBufferSize),
+      bytes_used_(kClusterHeaderSize),
+      cluster_timecode_(cluster_timecode),
+      finished_(false) {
+  memcpy(buffer_.get(), kClusterHeader, kClusterHeaderSize);
+
+  // Write the timecode into the header.
+  uint8* buf = buffer_.get() + kClusterTimecodeOffset;
+  for (int i = 7; i >= 0; --i) {
+    buf[i] = cluster_timecode & 0xff;
+    cluster_timecode >>= 8;
+  }
+}
+
+void ClusterBuilder::AddSimpleBlock(int track_num, int64 timecode, int flags,
+                                    const uint8* data, int size) {
+  DCHECK_GE(track_num, 0);
+  DCHECK_LE(track_num, 126);
+  DCHECK_GE(flags, 0);
+  DCHECK_LE(flags, 0xff);
+  DCHECK(data);
+  DCHECK_GT(size, 0);
+  DCHECK(!finished_);
+
+  int64 timecode_delta = timecode - cluster_timecode_;
+  DCHECK_GE(timecode_delta, -32768);
+  DCHECK_LE(timecode_delta, 32767);
+
+  int block_size = 4 + size;
+  int bytes_needed = kSimpleBlockHeaderSize + block_size;
+  if (bytes_needed > (buffer_size_ - bytes_used_))
+    ExtendBuffer(bytes_needed);
+
+  uint8* buf = buffer_.get() + bytes_used_;
+  int block_offset = bytes_used_;
+  memcpy(buf, kSimpleBlockHeader, kSimpleBlockHeaderSize);
+  UpdateUInt64(block_offset + kSimpleBlockSizeOffset, block_size);
+  buf += kSimpleBlockHeaderSize;
+
+  buf[0] = 0x80 | (track_num & 0x7F);
+  buf[1] = (timecode_delta >> 8) & 0xff;
+  buf[2] = timecode_delta & 0xff;
+  buf[3] = flags & 0xff;
+  memcpy(buf + 4, data, size);
+
+  bytes_used_ += bytes_needed;
+}
+
+void ClusterBuilder::Finish() {

[scherkus (not reviewing), 2011/06/28 20:03:29]

any checks for calling Finish twice?

also what if Finish() returned an object (i.e., a Cluster) that contained+owned
the data+size, meaning ClusterBuilder was more like a factory that generates
clusters for a given timecode

[acolwell GONE FROM CHROMIUM, 2011/06/29 16:38:43]

Added a DCHECK, created Cluster object, & updated ChunkDemuxerTest

+  UpdateUInt64(kClusterSizeOffset, bytes_used_ - (kClusterSizeOffset + 8));
+  finished_ = true;
+}
+
+const uint8* ClusterBuilder::GetClusterData() const {
+  DCHECK(finished_) << "Finish() MUST be called before GetClusterData()";
+  return buffer_.get();
+}
+
+const int ClusterBuilder::GetClusterDataSize() const {
+  DCHECK(finished_) << "Finish() MUST be called before GetClusterDataSize()";
+  return bytes_used_;
+}
+
+void ClusterBuilder::ExtendBuffer(int bytes_needed) {
+  int new_buffer_size = 2 * buffer_size_;
+
+  while ((new_buffer_size - bytes_used_) < bytes_needed)
+    new_buffer_size *= 2;
+
+  scoped_array<uint8> new_buffer(new uint8[new_buffer_size]);
+
+  memcpy(new_buffer.get(), buffer_.get(), bytes_used_);
+  buffer_.reset(new_buffer.release());
+  buffer_size_ = new_buffer_size;
+}
+
+void ClusterBuilder::UpdateUInt64(int offset, int64 value) {
+  DCHECK_LE(offset + 7, buffer_size_);
+  uint8* buf = buffer_.get() + offset;
+
+  // Fill the last 7 bytes of size field in big-endian order.
+  for (int i = 7; i > 0; i--) {
+    buf[i] = value & 0xff;
+    value >>= 8;
+  }
+}
+
+}  // namespace media