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FFmpeg/libavformat/matroskaenc.c

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/*
* Matroska muxer
* Copyright (c) 2007 David Conrad
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "md5.h"
#include "riff.h"
#include "xiph.h"
#include "matroska.h"
typedef struct ebml_master {
offset_t pos; ///< absolute offset in the file where the master's elements start
int sizebytes; ///< how many bytes were reserved for the size
} ebml_master;
typedef struct mkv_seekhead_entry {
unsigned int elementid;
uint64_t segmentpos;
} mkv_seekhead_entry;
typedef struct mkv_seekhead {
offset_t filepos;
offset_t segment_offset; ///< the file offset to the beginning of the segment
int reserved_size; ///< -1 if appending to file
int max_entries;
mkv_seekhead_entry *entries;
int num_entries;
} mkv_seekhead;
typedef struct {
uint64_t pts;
int tracknum;
offset_t cluster_pos; ///< file offset of the cluster containing the block
} mkv_cuepoint;
typedef struct {
offset_t segment_offset;
mkv_cuepoint *entries;
int num_entries;
} mkv_cues;
typedef struct MatroskaMuxContext {
ebml_master segment;
offset_t segment_offset;
offset_t segment_uid;
ebml_master cluster;
offset_t cluster_pos; ///< file offset of the current cluster
uint64_t cluster_pts;
offset_t duration_offset;
uint64_t duration;
mkv_seekhead *main_seekhead;
mkv_seekhead *cluster_seekhead;
mkv_cues *cues;
struct AVMD5 *md5_ctx;
} MatroskaMuxContext;
// 2 bytes * 3 for EBML IDs, 3 1-byte EBML lengths, 8 bytes for 64 bit
// offset, 4 bytes for target EBML ID
#define MAX_SEEKENTRY_SIZE 21
// per-cuepoint-track - 3 1-byte EBML IDs, 3 1-byte EBML sizes, 2
// 8-byte uint max
#define MAX_CUETRACKPOS_SIZE 22
// per-cuepoint - 2 1-byte EBML IDs, 2 1-byte EBML sizes, 8-byte uint max
#define MAX_CUEPOINT_SIZE(num_tracks) 12 + MAX_CUETRACKPOS_SIZE*num_tracks
static int ebml_id_size(unsigned int id)
{
return (av_log2(id+1)-1)/7+1;
}
static void put_ebml_id(ByteIOContext *pb, unsigned int id)
{
int i = ebml_id_size(id);
while (i--)
put_byte(pb, id >> (i*8));
}
/**
* Write an EBML size meaning "unknown size"
*
* @param bytes The number of bytes the size should occupy. Maximum of 8.
*/
static void put_ebml_size_unknown(ByteIOContext *pb, int bytes)
{
bytes = FFMIN(bytes, 8);
put_byte(pb, 0x1ff >> bytes);
while (--bytes)
put_byte(pb, 0xff);
}
/**
* Calculate how many bytes are needed to represent a given size in EBML.
*/
static int ebml_size_bytes(uint64_t size)
{
int bytes = 1;
while ((size+1) >> bytes*7) bytes++;
return bytes;
}
/**
* Write a size in EBML variable length format.
*
* @param bytes The number of bytes that need to be used to write the size.
* If zero, any number of bytes can be used.
*/
static void put_ebml_size(ByteIOContext *pb, uint64_t size, int bytes)
{
int i, needed_bytes = ebml_size_bytes(size);
// sizes larger than this are currently undefined in EBML
// so write "unknown" size
if (size >= (1ULL<<56)-1) {
put_ebml_size_unknown(pb, 1);
return;
}
if (bytes == 0)
// don't care how many bytes are used, so use the min
bytes = needed_bytes;
else if (needed_bytes > bytes) {
// the bytes needed to write the given size would exceed the bytes
// that we need to use, so write unknown size. This shouldn't happen.
av_log(NULL, AV_LOG_WARNING, "Size of %" PRIu64 " needs %d bytes but only %d bytes reserved\n",
size, needed_bytes, bytes);
put_ebml_size_unknown(pb, bytes);
return;
}
size |= 1ULL << bytes*7;
for (i = bytes - 1; i >= 0; i--)
put_byte(pb, size >> i*8);
}
static void put_ebml_uint(ByteIOContext *pb, unsigned int elementid, uint64_t val)
{
int i, bytes = 1;
while (val >> bytes*8) bytes++;
put_ebml_id(pb, elementid);
put_ebml_size(pb, bytes, 0);
for (i = bytes - 1; i >= 0; i--)
put_byte(pb, val >> i*8);
}
static void put_ebml_float(ByteIOContext *pb, unsigned int elementid, double val)
{
put_ebml_id(pb, elementid);
put_ebml_size(pb, 8, 0);
put_be64(pb, av_dbl2int(val));
}
static void put_ebml_binary(ByteIOContext *pb, unsigned int elementid,
const uint8_t *buf, int size)
{
put_ebml_id(pb, elementid);
put_ebml_size(pb, size, 0);
put_buffer(pb, buf, size);
}
static void put_ebml_string(ByteIOContext *pb, unsigned int elementid, const char *str)
{
put_ebml_binary(pb, elementid, str, strlen(str));
}
/**
* Writes a void element of a given size. Useful for reserving space in
* the file to be written to later.
*
* @param size The number of bytes to reserve, which must be at least 2.
*/
static void put_ebml_void(ByteIOContext *pb, uint64_t size)
{
offset_t currentpos = url_ftell(pb);
if (size < 2)
return;
put_ebml_id(pb, EBML_ID_VOID);
// we need to subtract the length needed to store the size from the
// size we need to reserve so 2 cases, we use 8 bytes to store the
// size if possible, 1 byte otherwise
if (size < 10)
put_ebml_size(pb, size-1, 0);
else
put_ebml_size(pb, size-9, 8);
url_fseek(pb, currentpos + size, SEEK_SET);
}
static ebml_master start_ebml_master(ByteIOContext *pb, unsigned int elementid, uint64_t expectedsize)
{
int bytes = expectedsize ? ebml_size_bytes(expectedsize) : 8;
put_ebml_id(pb, elementid);
put_ebml_size_unknown(pb, bytes);
return (ebml_master){ url_ftell(pb), bytes };
}
static void end_ebml_master(ByteIOContext *pb, ebml_master master)
{
offset_t pos = url_ftell(pb);
url_fseek(pb, master.pos - master.sizebytes, SEEK_SET);
put_ebml_size(pb, pos - master.pos, master.sizebytes);
url_fseek(pb, pos, SEEK_SET);
}
static void put_xiph_size(ByteIOContext *pb, int size)
{
int i;
for (i = 0; i < size / 255; i++)
put_byte(pb, 255);
put_byte(pb, size % 255);
}
/**
* Initialize a mkv_seekhead element to be ready to index level 1 Matroska
* elements. If a maximum number of elements is specified, enough space
* will be reserved at the current file location to write a seek head of
* that size.
*
* @param segment_offset The absolute offset to the position in the file
* where the segment begins
* @param numelements the maximum number of elements that will be indexed
* by this seek head, 0 if unlimited.
*/
static mkv_seekhead * mkv_start_seekhead(ByteIOContext *pb, offset_t segment_offset, int numelements)
{
mkv_seekhead *new_seekhead = av_mallocz(sizeof(mkv_seekhead));
if (new_seekhead == NULL)
return NULL;
new_seekhead->segment_offset = segment_offset;
if (numelements > 0) {
new_seekhead->filepos = url_ftell(pb);
// 21 bytes max for a seek entry, 10 bytes max for the SeekHead ID
// and size, and 3 bytes to guarantee that an EBML void element
// will fit afterwards
new_seekhead->reserved_size = numelements * MAX_SEEKENTRY_SIZE + 13;
new_seekhead->max_entries = numelements;
put_ebml_void(pb, new_seekhead->reserved_size);
}
return new_seekhead;
}
static int mkv_add_seekhead_entry(mkv_seekhead *seekhead, unsigned int elementid, uint64_t filepos)
{
mkv_seekhead_entry *entries = seekhead->entries;
int new_entry = seekhead->num_entries;
// don't store more elements than we reserved space for
if (seekhead->max_entries > 0 && seekhead->max_entries <= seekhead->num_entries)
return -1;
entries = av_realloc(entries, (seekhead->num_entries + 1) * sizeof(mkv_seekhead_entry));
if (entries == NULL)
return -1;
entries[new_entry].elementid = elementid;
entries[new_entry].segmentpos = filepos - seekhead->segment_offset;
seekhead->entries = entries;
seekhead->num_entries++;
return 0;
}
/**
* Write the seek head to the file and free it. If a maximum number of
* elements was specified to mkv_start_seekhead(), the seek head will
* be written at the location reserved for it. Otherwise, it is written
* at the current location in the file.
*
* @return the file offset where the seekhead was written
*/
static offset_t mkv_write_seekhead(ByteIOContext *pb, mkv_seekhead *seekhead)
{
ebml_master metaseek, seekentry;
offset_t currentpos;
int i;
currentpos = url_ftell(pb);
if (seekhead->reserved_size > 0)
url_fseek(pb, seekhead->filepos, SEEK_SET);
metaseek = start_ebml_master(pb, MATROSKA_ID_SEEKHEAD, seekhead->reserved_size);
for (i = 0; i < seekhead->num_entries; i++) {
mkv_seekhead_entry *entry = &seekhead->entries[i];
seekentry = start_ebml_master(pb, MATROSKA_ID_SEEKENTRY, MAX_SEEKENTRY_SIZE);
put_ebml_id(pb, MATROSKA_ID_SEEKID);
put_ebml_size(pb, ebml_id_size(entry->elementid), 0);
put_ebml_id(pb, entry->elementid);
put_ebml_uint(pb, MATROSKA_ID_SEEKPOSITION, entry->segmentpos);
end_ebml_master(pb, seekentry);
}
end_ebml_master(pb, metaseek);
if (seekhead->reserved_size > 0) {
uint64_t remaining = seekhead->filepos + seekhead->reserved_size - url_ftell(pb);
put_ebml_void(pb, remaining);
url_fseek(pb, currentpos, SEEK_SET);
currentpos = seekhead->filepos;
}
av_free(seekhead->entries);
av_free(seekhead);
return currentpos;
}
static mkv_cues * mkv_start_cues(offset_t segment_offset)
{
mkv_cues *cues = av_mallocz(sizeof(mkv_cues));
if (cues == NULL)
return NULL;
cues->segment_offset = segment_offset;
return cues;
}
static int mkv_add_cuepoint(mkv_cues *cues, AVPacket *pkt, offset_t cluster_pos)
{
mkv_cuepoint *entries = cues->entries;
int new_entry = cues->num_entries;
entries = av_realloc(entries, (cues->num_entries + 1) * sizeof(mkv_cuepoint));
if (entries == NULL)
return -1;
entries[new_entry].pts = pkt->pts;
entries[new_entry].tracknum = pkt->stream_index + 1;
entries[new_entry].cluster_pos = cluster_pos - cues->segment_offset;
cues->entries = entries;
cues->num_entries++;
return 0;
}
static offset_t mkv_write_cues(ByteIOContext *pb, mkv_cues *cues, int num_tracks)
{
ebml_master cues_element;
offset_t currentpos;
int i, j;
currentpos = url_ftell(pb);
cues_element = start_ebml_master(pb, MATROSKA_ID_CUES, 0);
for (i = 0; i < cues->num_entries; i++) {
ebml_master cuepoint, track_positions;
mkv_cuepoint *entry = &cues->entries[i];
uint64_t pts = entry->pts;
cuepoint = start_ebml_master(pb, MATROSKA_ID_POINTENTRY, MAX_CUEPOINT_SIZE(num_tracks));
put_ebml_uint(pb, MATROSKA_ID_CUETIME, pts);
// put all the entries from different tracks that have the exact same
// timestamp into the same CuePoint
for (j = 0; j < cues->num_entries - i && entry[j].pts == pts; j++) {
track_positions = start_ebml_master(pb, MATROSKA_ID_CUETRACKPOSITION, MAX_CUETRACKPOS_SIZE);
put_ebml_uint(pb, MATROSKA_ID_CUETRACK , entry[j].tracknum );
put_ebml_uint(pb, MATROSKA_ID_CUECLUSTERPOSITION, entry[j].cluster_pos);
end_ebml_master(pb, track_positions);
}
i += j - 1;
end_ebml_master(pb, cuepoint);
}
end_ebml_master(pb, cues_element);
av_free(cues->entries);
av_free(cues);
return currentpos;
}
static int put_xiph_codecpriv(ByteIOContext *pb, AVCodecContext *codec)
{
ebml_master codecprivate;
uint8_t *header_start[3];
int header_len[3];
int first_header_size;
int j;
if (codec->codec_id == CODEC_ID_VORBIS)
first_header_size = 30;
else
first_header_size = 42;
if (ff_split_xiph_headers(codec->extradata, codec->extradata_size,
first_header_size, header_start, header_len) < 0) {
av_log(codec, AV_LOG_ERROR, "Extradata corrupt.\n");
return -1;
}
codecprivate = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE, 0);
put_byte(pb, 2); // number packets - 1
for (j = 0; j < 2; j++) {
put_xiph_size(pb, header_len[j]);
}
for (j = 0; j < 3; j++)
put_buffer(pb, header_start[j], header_len[j]);
end_ebml_master(pb, codecprivate);
return 0;
}
#define FLAC_STREAMINFO_SIZE 34
static int put_flac_codecpriv(ByteIOContext *pb, AVCodecContext *codec)
{
ebml_master codecpriv = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE, 0);
// if the extradata_size is greater than FLAC_STREAMINFO_SIZE,
// assume that it's in Matroska's format already
if (codec->extradata_size < FLAC_STREAMINFO_SIZE) {
av_log(codec, AV_LOG_ERROR, "Invalid FLAC extradata\n");
return -1;
} else if (codec->extradata_size == FLAC_STREAMINFO_SIZE) {
// only the streaminfo packet
put_byte(pb, 0);
put_xiph_size(pb, codec->extradata_size);
av_log(codec, AV_LOG_ERROR, "Only one packet\n");
}
put_buffer(pb, codec->extradata, codec->extradata_size);
end_ebml_master(pb, codecpriv);
return 0;
}
static void get_aac_sample_rates(AVCodecContext *codec, int *sample_rate, int *output_sample_rate)
{
static const int aac_sample_rates[] = {
96000, 88200, 64000, 48000, 44100, 32000,
24000, 22050, 16000, 12000, 11025, 8000,
};
int sri;
if (codec->extradata_size < 2) {
av_log(codec, AV_LOG_WARNING, "no AAC extradata, unable to determine samplerate\n");
return;
}
sri = ((codec->extradata[0] << 1) & 0xE) | (codec->extradata[1] >> 7);
if (sri > 12) {
av_log(codec, AV_LOG_WARNING, "AAC samplerate index out of bounds\n");
return;
}
*sample_rate = aac_sample_rates[sri];
// if sbr, get output sample rate as well
if (codec->extradata_size == 5) {
sri = (codec->extradata[4] >> 3) & 0xF;
if (sri > 12) {
av_log(codec, AV_LOG_WARNING, "AAC output samplerate index out of bounds\n");
return;
}
*output_sample_rate = aac_sample_rates[sri];
}
}
static int mkv_write_tracks(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
ByteIOContext *pb = &s->pb;
ebml_master tracks;
int i, j;
if (mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_TRACKS, url_ftell(pb)) < 0)
return -1;
tracks = start_ebml_master(pb, MATROSKA_ID_TRACKS, 0);
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
AVCodecContext *codec = st->codec;
ebml_master subinfo, track;
int native_id = 0;
int bit_depth = av_get_bits_per_sample(codec->codec_id);
int sample_rate = codec->sample_rate;
int output_sample_rate = 0;
if (!bit_depth)
bit_depth = av_get_bits_per_sample_format(codec->sample_fmt);
if (codec->codec_id == CODEC_ID_AAC)
get_aac_sample_rates(codec, &sample_rate, &output_sample_rate);
track = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY, 0);
put_ebml_uint (pb, MATROSKA_ID_TRACKNUMBER , i + 1);
put_ebml_uint (pb, MATROSKA_ID_TRACKUID , i + 1);
put_ebml_uint (pb, MATROSKA_ID_TRACKFLAGLACING , 0); // no lacing (yet)
if (st->language[0])
put_ebml_string(pb, MATROSKA_ID_TRACKLANGUAGE, st->language);
else
put_ebml_string(pb, MATROSKA_ID_TRACKLANGUAGE, "und");
// look for a codec id string specific to mkv to use,
// if none are found, use AVI codes
for (j = 0; ff_mkv_codec_tags[j].id != CODEC_ID_NONE; j++) {
if (ff_mkv_codec_tags[j].id == codec->codec_id) {
put_ebml_string(pb, MATROSKA_ID_CODECID, ff_mkv_codec_tags[j].str);
native_id = 1;
break;
}
}
if (native_id) {
if (codec->codec_id == CODEC_ID_VORBIS || codec->codec_id == CODEC_ID_THEORA) {
if (put_xiph_codecpriv(pb, codec) < 0)
return -1;
} else if (codec->codec_id == CODEC_ID_FLAC) {
if (put_flac_codecpriv(pb, codec) < 0)
return -1;
} else if (codec->extradata_size) {
put_ebml_binary(pb, MATROSKA_ID_CODECPRIVATE, codec->extradata, codec->extradata_size);
}
}
switch (codec->codec_type) {
case CODEC_TYPE_VIDEO:
put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_VIDEO);
if (!native_id) {
ebml_master bmp_header;
// if there is no mkv-specific codec id, use VFW mode
if (!codec->codec_tag)
codec->codec_tag = codec_get_tag(codec_bmp_tags, codec->codec_id);
put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC);
bmp_header = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE, 0);
put_bmp_header(pb, codec, codec_bmp_tags, 0);
end_ebml_master(pb, bmp_header);
}
subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKVIDEO, 0);
// XXX: interlace flag?
put_ebml_uint (pb, MATROSKA_ID_VIDEOPIXELWIDTH , codec->width);
put_ebml_uint (pb, MATROSKA_ID_VIDEOPIXELHEIGHT, codec->height);
if (codec->sample_aspect_ratio.num) {
AVRational dar = av_mul_q(codec->sample_aspect_ratio, (AVRational){codec->width, codec->height});
put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , dar.num);
put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, dar.den);
}
end_ebml_master(pb, subinfo);
break;
case CODEC_TYPE_AUDIO:
put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_AUDIO);
if (!native_id) {
ebml_master wav_header;
// no mkv-specific ID, use ACM mode
codec->codec_tag = codec_get_tag(codec_wav_tags, codec->codec_id);
if (!codec->codec_tag) {
av_log(s, AV_LOG_ERROR, "no codec id found for stream %d", i);
return -1;
}
put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_AUDIO_ACM);
wav_header = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE, 0);
put_wav_header(pb, codec);
end_ebml_master(pb, wav_header);
}
subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKAUDIO, 0);
put_ebml_uint (pb, MATROSKA_ID_AUDIOCHANNELS , codec->channels);
put_ebml_float (pb, MATROSKA_ID_AUDIOSAMPLINGFREQ, sample_rate);
if (output_sample_rate)
put_ebml_float(pb, MATROSKA_ID_AUDIOOUTSAMPLINGFREQ, output_sample_rate);
if (bit_depth)
put_ebml_uint(pb, MATROSKA_ID_AUDIOBITDEPTH, bit_depth);
end_ebml_master(pb, subinfo);
break;
case CODEC_TYPE_SUBTITLE:
put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_SUBTITLE);
break;
default:
av_log(s, AV_LOG_ERROR, "Only audio and video are supported for Matroska.");
break;
}
end_ebml_master(pb, track);
// ms precision is the de-facto standard timescale for mkv files
av_set_pts_info(st, 64, 1, 1000);
}
end_ebml_master(pb, tracks);
return 0;
}
static int mkv_write_header(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
ByteIOContext *pb = &s->pb;
ebml_master ebml_header, segment_info;
mkv->md5_ctx = av_mallocz(av_md5_size);
av_md5_init(mkv->md5_ctx);
ebml_header = start_ebml_master(pb, EBML_ID_HEADER, 0);
put_ebml_uint (pb, EBML_ID_EBMLVERSION , 1);
put_ebml_uint (pb, EBML_ID_EBMLREADVERSION , 1);
put_ebml_uint (pb, EBML_ID_EBMLMAXIDLENGTH , 4);
put_ebml_uint (pb, EBML_ID_EBMLMAXSIZELENGTH , 8);
put_ebml_string (pb, EBML_ID_DOCTYPE , "matroska");
put_ebml_uint (pb, EBML_ID_DOCTYPEVERSION , 2);
put_ebml_uint (pb, EBML_ID_DOCTYPEREADVERSION , 2);
end_ebml_master(pb, ebml_header);
mkv->segment = start_ebml_master(pb, MATROSKA_ID_SEGMENT, 0);
mkv->segment_offset = url_ftell(pb);
// we write 2 seek heads - one at the end of the file to point to each
// cluster, and one at the beginning to point to all other level one
// elements (including the seek head at the end of the file), which
// isn't more than 10 elements if we only write one of each other
// currently defined level 1 element
mkv->main_seekhead = mkv_start_seekhead(pb, mkv->segment_offset, 10);
mkv->cluster_seekhead = mkv_start_seekhead(pb, mkv->segment_offset, 0);
if (mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_INFO, url_ftell(pb)) < 0)
return -1;
segment_info = start_ebml_master(pb, MATROSKA_ID_INFO, 0);
put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000);
if (strlen(s->title))
put_ebml_string(pb, MATROSKA_ID_TITLE, s->title);
if (!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) {
put_ebml_string(pb, MATROSKA_ID_MUXINGAPP , LIBAVFORMAT_IDENT);
put_ebml_string(pb, MATROSKA_ID_WRITINGAPP, LIBAVFORMAT_IDENT);
// reserve space to write the segment UID later
mkv->segment_uid = url_ftell(pb);
put_ebml_void(pb, 19);
}
// reserve space for the duration
mkv->duration = 0;
mkv->duration_offset = url_ftell(pb);
put_ebml_void(pb, 11); // assumes double-precision float to be written
end_ebml_master(pb, segment_info);
if (mkv_write_tracks(s) < 0)
return -1;
if (mkv_add_seekhead_entry(mkv->cluster_seekhead, MATROSKA_ID_CLUSTER, url_ftell(pb)) < 0)
return -1;
mkv->cluster_pos = url_ftell(pb);
mkv->cluster = start_ebml_master(pb, MATROSKA_ID_CLUSTER, 0);
put_ebml_uint(pb, MATROSKA_ID_CLUSTERTIMECODE, 0);
mkv->cluster_pts = 0;
mkv->cues = mkv_start_cues(mkv->segment_offset);
if (mkv->cues == NULL)
return -1;
return 0;
}
static int mkv_block_size(AVPacket *pkt)
{
int size = 4; // track num + timecode + flags
return size + pkt->size;
}
static int mkv_blockgroup_size(AVPacket *pkt)
{
int size = mkv_block_size(pkt);
size += ebml_size_bytes(size);
size += 2; // EBML ID for block and block duration
size += 8; // max size of block duration
size += ebml_size_bytes(size);
size += 1; // blockgroup EBML ID
return size;
}
static void mkv_write_block(AVFormatContext *s, unsigned int blockid, AVPacket *pkt, int flags)
{
MatroskaMuxContext *mkv = s->priv_data;
ByteIOContext *pb = &s->pb;
av_log(s, AV_LOG_DEBUG, "Writing block at offset %" PRIu64 ", size %d, pts %" PRId64 ", dts %" PRId64 ", duration %d, flags %d\n",
url_ftell(pb), pkt->size, pkt->pts, pkt->dts, pkt->duration, flags);
put_ebml_id(pb, blockid);
put_ebml_size(pb, mkv_block_size(pkt), 0);
put_byte(pb, 0x80 | (pkt->stream_index + 1)); // this assumes stream_index is less than 126
put_be16(pb, pkt->pts - mkv->cluster_pts);
put_byte(pb, flags);
put_buffer(pb, pkt->data, pkt->size);
}
static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
{
MatroskaMuxContext *mkv = s->priv_data;
ByteIOContext *pb = &s->pb;
AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
int keyframe = !!(pkt->flags & PKT_FLAG_KEY);
// start a new cluster every 5 MB or 5 sec
if (url_ftell(pb) > mkv->cluster_pos + 5*1024*1024 || pkt->pts > mkv->cluster_pts + 5000) {
av_log(s, AV_LOG_DEBUG, "Starting new cluster at offset %" PRIu64 " bytes, pts %" PRIu64 "\n", url_ftell(pb), pkt->pts);
end_ebml_master(pb, mkv->cluster);
if (mkv_add_seekhead_entry(mkv->cluster_seekhead, MATROSKA_ID_CLUSTER, url_ftell(pb)) < 0)
return -1;
mkv->cluster_pos = url_ftell(pb);
mkv->cluster = start_ebml_master(pb, MATROSKA_ID_CLUSTER, 0);
put_ebml_uint(pb, MATROSKA_ID_CLUSTERTIMECODE, pkt->pts);
mkv->cluster_pts = pkt->pts;
av_md5_update(mkv->md5_ctx, pkt->data, FFMIN(200, pkt->size));
}
if (codec->codec_type != CODEC_TYPE_SUBTITLE) {
mkv_write_block(s, MATROSKA_ID_SIMPLEBLOCK, pkt, keyframe << 7);
} else {
ebml_master blockgroup = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP, mkv_blockgroup_size(pkt));
mkv_write_block(s, MATROSKA_ID_BLOCK, pkt, 0);
put_ebml_uint(pb, MATROSKA_ID_DURATION, pkt->duration);
end_ebml_master(pb, blockgroup);
}
if (codec->codec_type == CODEC_TYPE_VIDEO && keyframe) {
if (mkv_add_cuepoint(mkv->cues, pkt, mkv->cluster_pos) < 0)
return -1;
}
mkv->duration = pkt->pts + pkt->duration;
return 0;
}
static int mkv_write_trailer(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
ByteIOContext *pb = &s->pb;
offset_t currentpos, second_seekhead, cuespos;
end_ebml_master(pb, mkv->cluster);
cuespos = mkv_write_cues(pb, mkv->cues, s->nb_streams);
second_seekhead = mkv_write_seekhead(pb, mkv->cluster_seekhead);
mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CUES , cuespos);
mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_SEEKHEAD, second_seekhead);
mkv_write_seekhead(pb, mkv->main_seekhead);
// update the duration
av_log(s, AV_LOG_DEBUG, "end duration = %" PRIu64 "\n", mkv->duration);
currentpos = url_ftell(pb);
url_fseek(pb, mkv->duration_offset, SEEK_SET);
put_ebml_float(pb, MATROSKA_ID_DURATION, mkv->duration);
// write the md5sum of some frames as the segment UID
if (!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) {
uint8_t segment_uid[16];
av_md5_final(mkv->md5_ctx, segment_uid);
url_fseek(pb, mkv->segment_uid, SEEK_SET);
put_ebml_binary(pb, MATROSKA_ID_SEGMENTUID, segment_uid, 16);
}
url_fseek(pb, currentpos, SEEK_SET);
end_ebml_master(pb, mkv->segment);
av_free(mkv->md5_ctx);
return 0;
}
AVOutputFormat matroska_muxer = {
"matroska",
"Matroska File Format",
"video/x-matroska",
"mkv",
sizeof(MatroskaMuxContext),
CODEC_ID_MP2,
CODEC_ID_MPEG4,
mkv_write_header,
mkv_write_packet,
mkv_write_trailer,
.codec_tag = (const AVCodecTag*[]){codec_bmp_tags, codec_wav_tags, 0},
.subtitle_codec = CODEC_ID_TEXT,
};
AVOutputFormat matroska_audio_muxer = {
"matroska",
"Matroska File Format",
"audio/x-matroska",
"mka",
sizeof(MatroskaMuxContext),
CODEC_ID_MP2,
CODEC_ID_NONE,
mkv_write_header,
mkv_write_packet,
mkv_write_trailer,
.codec_tag = (const AVCodecTag*[]){codec_wav_tags, 0},
};