void EbmlComposer::GenerateHeader()
{
// Write the EBML header.
EbmlGlobal ebml;
// The WEbM header default size usually smaller than 1k.
auto buffer = MakeUnique<uint8_t[]>(DEFAULT_HEADER_SIZE +
mCodecPrivateData.Length());
ebml.buf = buffer.get();
ebml.offset = 0;
writeHeader(&ebml);
{
EbmlLoc segEbmlLoc, ebmlLocseg, ebmlLoc;
Ebml_StartSubElement(&ebml, &segEbmlLoc, Segment);
{
Ebml_StartSubElement(&ebml, &ebmlLocseg, SeekHead);
// Todo: We don't know the exact sizes of encoded data and
// ignore this section.
Ebml_EndSubElement(&ebml, &ebmlLocseg);
writeSegmentInformation(&ebml, &ebmlLoc, TIME_CODE_SCALE, 0);
{
EbmlLoc trackLoc;
Ebml_StartSubElement(&ebml, &trackLoc, Tracks);
{
// Video
if (mWidth > 0 && mHeight > 0) {
writeVideoTrack(&ebml, 0x1, 0, "V_VP8",
mWidth, mHeight,
mDisplayWidth, mDisplayHeight, mFrameRate);
}
// Audio
if (mCodecPrivateData.Length() > 0) {
// Extract the pre-skip from mCodecPrivateData
// then convert it to nanoseconds.
// Details in OpusTrackEncoder.cpp.
mCodecDelay =
(uint64_t)LittleEndian::readUint16(mCodecPrivateData.Elements() + 10)
* PR_NSEC_PER_SEC / 48000;
// Fixed 80ms, convert into nanoseconds.
uint64_t seekPreRoll = 80 * PR_NSEC_PER_MSEC;
writeAudioTrack(&ebml, 0x2, 0x0, "A_OPUS", mSampleFreq,
mChannels, mCodecDelay, seekPreRoll,
mCodecPrivateData.Elements(),
mCodecPrivateData.Length());
}
}
Ebml_EndSubElement(&ebml, &trackLoc);
}
}
// The Recording length is unknown and
// ignore write the whole Segment element size
}
MOZ_ASSERT(ebml.offset <= DEFAULT_HEADER_SIZE + mCodecPrivateData.Length(),
"write more data > EBML_BUFFER_SIZE");
auto block = mClusterBuffs.AppendElement();
block->SetLength(ebml.offset);
memcpy(block->Elements(), ebml.buf, ebml.offset);
mFlushState |= FLUSH_METADATA;
}
void EbmlComposer::GenerateHeader()
{
// Write the EBML header.
EbmlGlobal ebml;
// The WEbM header default size usually smaller than 1k.
nsAutoArrayPtr<uint8_t> buffer(new uint8_t[DEFAULT_HEADER_SIZE +
mCodecPrivateData.Length()]);
ebml.buf = buffer.get();
ebml.offset = 0;
writeHeader(&ebml);
{
EbmlLoc segEbmlLoc, ebmlLocseg, ebmlLoc;
Ebml_StartSubElement(&ebml, &segEbmlLoc, Segment);
{
Ebml_StartSubElement(&ebml, &ebmlLocseg, SeekHead);
// Todo: We don't know the exact sizes of encoded data and
// ignore this section.
Ebml_EndSubElement(&ebml, &ebmlLocseg);
writeSegmentInformation(&ebml, &ebmlLoc, TIME_CODE_SCALE, 0);
{
EbmlLoc trackLoc;
Ebml_StartSubElement(&ebml, &trackLoc, Tracks);
{
// Video
if (mWidth > 0 && mHeight > 0) {
writeVideoTrack(&ebml, 0x1, 0, "V_VP8",
mWidth, mHeight,
mDisplayWidth, mDisplayHeight, mFrameRate);
}
// Audio
if (mCodecPrivateData.Length() > 0) {
writeAudioTrack(&ebml, 0x2, 0x0, "A_VORBIS", mSampleFreq,
mChannels, mCodecPrivateData.Elements(),
mCodecPrivateData.Length());
}
}
Ebml_EndSubElement(&ebml, &trackLoc);
}
}
// The Recording length is unknown and
// ignore write the whole Segment element size
}
MOZ_ASSERT(ebml.offset <= DEFAULT_HEADER_SIZE + mCodecPrivateData.Length(),
"write more data > EBML_BUFFER_SIZE");
auto block = mClusterBuffs.AppendElement();
block->SetLength(ebml.offset);
memcpy(block->Elements(), ebml.buf, ebml.offset);
mFlushState |= FLUSH_METADATA;
}
int main(int argc, char *argv[]) {
// init the datatype we're using for ebml output
unsigned char data[8192];
EbmlGlobal ebml;
ebml.buf = data;
ebml.offset = 0;
ebml.length = 8192;
writeHeader(&ebml);
{
EbmlLoc startSegment;
Ebml_StartSubElement(&ebml, &startSegment, Segment); // segment
{
// segment info
EbmlLoc startInfo;
Ebml_StartSubElement(&ebml, &startInfo, Info);
Ebml_SerializeString(&ebml, 0x4D80, "muxingAppLibMkv");
Ebml_SerializeString(&ebml, 0x5741, "writingAppLibMkv");
Ebml_EndSubElement(&ebml, &startInfo);
}
{
EbmlLoc trackStart;
Ebml_StartSubElement(&ebml, &trackStart, Tracks);
writeVideoTrack(&ebml, 1, 1, "V_MS/VFW/FOURCC", 320, 240, 29.97);
// writeAudioTrack(&ebml,2,1, "A_VORBIS", 32000, 1, NULL, 0);
Ebml_EndSubElement(&ebml, &trackStart);
}
{
EbmlLoc clusterStart;
Ebml_StartSubElement(&ebml, &clusterStart, Cluster); // cluster
Ebml_SerializeUnsigned(&ebml, Timecode, 0);
unsigned char someData[4] = {1, 2, 3, 4};
writeSimpleBlock(&ebml, 1, 0, 1, 0, 0, someData, 4);
Ebml_EndSubElement(&ebml, &clusterStart);
} // end cluster
Ebml_EndSubElement(&ebml, &startSegment);
}
// dump ebml stuff to the file
FILE *file_out = fopen("test.mkv", "wb");
size_t bytesWritten = fwrite(data, 1, ebml.offset, file_out);
fclose(file_out);
return 0;
}
