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ffmpeg / libavformat / matroskaenc.c @ 663a5d9d

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1
/*
2
 * Matroska file muxer
3
 * Copyright (c) 2007 David Conrad
4
 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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22
#include "avformat.h"
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#include "riff.h"
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#include "xiph.h"
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#include "matroska.h"
26

    
27
typedef struct mkv_seekhead_entry {
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    unsigned int    elementid;
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    uint64_t        segmentpos;
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} mkv_seekhead_entry;
31

    
32
typedef struct mkv_seekhead {
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    offset_t                filepos;
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    offset_t                segment_offset;     ///< the file offset to the beginning of the segment
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    int                     reserved_size;      ///< -1 if appending to file
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    int                     max_entries;
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    mkv_seekhead_entry      *entries;
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    int                     num_entries;
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} mkv_seekhead;
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41
typedef struct {
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    uint64_t        pts;
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    int             tracknum;
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    offset_t        cluster_pos;        ///< file offset of the cluster containing the block
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} mkv_cuepoint;
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47
typedef struct {
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    offset_t        segment_offset;
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    mkv_cuepoint    *entries;
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    int             num_entries;
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} mkv_cues;
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typedef struct MatroskaMuxContext {
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    offset_t        segment;
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    offset_t        segment_offset;
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    offset_t        cluster;
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    offset_t        cluster_pos;        ///< file offset of the current cluster
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    uint64_t        cluster_pts;
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    offset_t        duration_offset;
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    uint64_t        duration;
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    mkv_seekhead    *main_seekhead;
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    mkv_seekhead    *cluster_seekhead;
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    mkv_cues        *cues;
64
} MatroskaMuxContext;
65

    
66
static void put_ebml_id(ByteIOContext *pb, unsigned int id)
67
{
68
    if (id >= 0x3fffff)
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        put_byte(pb, id >> 24);
70
    if (id >= 0x7fff)
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        put_byte(pb, id >> 16);
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    if (id >= 0xff)
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        put_byte(pb, id >> 8);
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    put_byte(pb, id);
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}
76

    
77
static int ebml_id_size(unsigned int id)
78
{
79
    return (av_log2(id+1)-1)/7+1;
80
}
81

    
82
// XXX: test this thoroughly and get rid of minbytes hack (currently needed to
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// use up all of the space reserved in start_ebml_master)
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static void put_ebml_size(ByteIOContext *pb, uint64_t size, int minbytes)
85
{
86
    int bytes = minbytes;
87

    
88
    // sizes larger than this are currently undefined in EBML
89
    // so write "unknown" size
90
    size = FFMIN(size, (1ULL<<56)-1);
91

    
92
    while (size >> (bytes*7 + 7)) bytes++;
93

    
94
    put_byte(pb, (0x80 >> bytes) | (size >> bytes*8));
95
    for (bytes -= 1; bytes >= 0; bytes--)
96
        put_byte(pb, size >> bytes*8);
97
}
98

    
99
static void put_ebml_uint(ByteIOContext *pb, unsigned int elementid, uint64_t val)
100
{
101
    int bytes = 1;
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    while (val >> bytes*8) bytes++;
103

    
104
    put_ebml_id(pb, elementid);
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    put_ebml_size(pb, bytes, 0);
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    for (bytes -= 1; bytes >= 0; bytes--)
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        put_byte(pb, val >> bytes*8);
108
}
109

    
110
static void put_ebml_float(ByteIOContext *pb, unsigned int elementid, double val)
111
{
112
    // XXX: single-precision floats?
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    put_ebml_id(pb, elementid);
114
    put_ebml_size(pb, 8, 0);
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    put_be64(pb, av_dbl2int(val));
116
}
117

    
118
static void put_ebml_binary(ByteIOContext *pb, unsigned int elementid,
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                            const uint8_t *buf, int size)
120
{
121
    put_ebml_id(pb, elementid);
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    put_ebml_size(pb, size, 0);
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    put_buffer(pb, buf, size);
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}
125

    
126
static void put_ebml_string(ByteIOContext *pb, unsigned int elementid, const char *str)
127
{
128
    put_ebml_binary(pb, elementid, str, strlen(str));
129
}
130

    
131
// this reserves exactly the amount of space specified by size, which must be at least 2
132
static void put_ebml_void(ByteIOContext *pb, uint64_t size)
133
{
134
    offset_t currentpos = url_ftell(pb);
135

    
136
    if (size < 2)
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        return;
138

    
139
    put_ebml_id(pb, EBML_ID_VOID);
140
    // we need to subtract the length needed to store the size from the size we need to reserve
141
    // so 2 cases, we use 8 bytes to store the size if possible, 1 byte otherwise
142
    if (size < 10)
143
        put_ebml_size(pb, size-1, 0);
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    else
145
        put_ebml_size(pb, size-9, 7);
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    url_fseek(pb, currentpos + size, SEEK_SET);
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}
148

    
149
static offset_t start_ebml_master(ByteIOContext *pb, unsigned int elementid)
150
{
151
    put_ebml_id(pb, elementid);
152
    // XXX: this always reserves the maximum needed space to store any size value
153
    // we should be smarter (additional parameter for expected size?)
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    put_ebml_size(pb, (1ULL<<56)-1, 0);     // largest unknown size
155
    return url_ftell(pb);
156
}
157

    
158
static void end_ebml_master(ByteIOContext *pb, offset_t start)
159
{
160
    offset_t pos = url_ftell(pb);
161

    
162
    url_fseek(pb, start - 8, SEEK_SET);
163
    put_ebml_size(pb, pos - start, 7);
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    url_fseek(pb, pos, SEEK_SET);
165
}
166

    
167
// initializes a mkv_seekhead element to be ready to index level 1 matroska elements
168
// if numelements is greater than 0, it reserves enough space for that many elements
169
// at the current file position and writes the seekhead there, otherwise the seekhead
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// will be appended to the file when end_mkv_seekhead() is called
171
static mkv_seekhead * mkv_start_seekhead(ByteIOContext *pb, offset_t segment_offset, int numelements)
172
{
173
    mkv_seekhead *new_seekhead = av_mallocz(sizeof(mkv_seekhead));
174
    if (new_seekhead == NULL)
175
        return NULL;
176

    
177
    new_seekhead->segment_offset = segment_offset;
178

    
179
    if (numelements > 0) {
180
        new_seekhead->filepos = url_ftell(pb);
181
        // 21 bytes max for a seek entry, 10 bytes max for the SeekHead ID and size,
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        // and 3 bytes to guarantee that an EBML void element will fit afterwards
183
        // XXX: 28 bytes right now because begin_ebml_master() reserves more than necessary
184
        new_seekhead->reserved_size = numelements * 28 + 13;
185
        new_seekhead->max_entries = numelements;
186
        put_ebml_void(pb, new_seekhead->reserved_size);
187
    }
188
    return new_seekhead;
189
}
190

    
191
static int mkv_add_seekhead_entry(mkv_seekhead *seekhead, unsigned int elementid, uint64_t filepos)
192
{
193
    mkv_seekhead_entry *entries = seekhead->entries;
194
    int new_entry = seekhead->num_entries;
195

    
196
    // don't store more elements than we reserved space for
197
    if (seekhead->max_entries > 0 && seekhead->max_entries <= seekhead->num_entries)
198
        return -1;
199

    
200
    entries = av_realloc(entries, (seekhead->num_entries + 1) * sizeof(mkv_seekhead_entry));
201
    if (entries == NULL)
202
        return -1;
203

    
204
    entries[new_entry].elementid = elementid;
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    entries[new_entry].segmentpos = filepos - seekhead->segment_offset;
206

    
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    seekhead->entries = entries;
208
    seekhead->num_entries++;
209

    
210
    return 0;
211
}
212

    
213
// returns the file offset where the seekhead was written and frees the seekhead
214
static offset_t mkv_write_seekhead(ByteIOContext *pb, mkv_seekhead *seekhead)
215
{
216
    offset_t metaseek, seekentry, currentpos;
217
    int i;
218

    
219
    currentpos = url_ftell(pb);
220

    
221
    if (seekhead->reserved_size > 0)
222
        url_fseek(pb, seekhead->filepos, SEEK_SET);
223

    
224
    metaseek = start_ebml_master(pb, MATROSKA_ID_SEEKHEAD);
225
    for (i = 0; i < seekhead->num_entries; i++) {
226
        mkv_seekhead_entry *entry = &seekhead->entries[i];
227

    
228
        seekentry = start_ebml_master(pb, MATROSKA_ID_SEEKENTRY);
229

    
230
        put_ebml_id(pb, MATROSKA_ID_SEEKID);
231
        put_ebml_size(pb, ebml_id_size(entry->elementid), 0);
232
        put_ebml_id(pb, entry->elementid);
233

    
234
        put_ebml_uint(pb, MATROSKA_ID_SEEKPOSITION, entry->segmentpos);
235
        end_ebml_master(pb, seekentry);
236
    }
237
    end_ebml_master(pb, metaseek);
238

    
239
    if (seekhead->reserved_size > 0) {
240
        uint64_t remaining = seekhead->filepos + seekhead->reserved_size - url_ftell(pb);
241
        put_ebml_void(pb, remaining);
242
        url_fseek(pb, currentpos, SEEK_SET);
243

    
244
        currentpos = seekhead->filepos;
245
    }
246
    av_free(seekhead->entries);
247
    av_free(seekhead);
248

    
249
    return currentpos;
250
}
251

    
252
static mkv_cues * mkv_start_cues(offset_t segment_offset)
253
{
254
    mkv_cues *cues = av_mallocz(sizeof(mkv_cues));
255
    if (cues == NULL)
256
        return NULL;
257

    
258
    cues->segment_offset = segment_offset;
259
    return cues;
260
}
261

    
262
static int mkv_add_cuepoint(mkv_cues *cues, AVPacket *pkt, offset_t cluster_pos)
263
{
264
    mkv_cuepoint *entries = cues->entries;
265
    int new_entry = cues->num_entries;
266

    
267
    entries = av_realloc(entries, (cues->num_entries + 1) * sizeof(mkv_cuepoint));
268
    if (entries == NULL)
269
        return -1;
270

    
271
    entries[new_entry].pts = pkt->pts;
272
    entries[new_entry].tracknum = pkt->stream_index + 1;
273
    entries[new_entry].cluster_pos = cluster_pos - cues->segment_offset;
274

    
275
    cues->entries = entries;
276
    cues->num_entries++;
277
    return 0;
278
}
279

    
280
static offset_t mkv_write_cues(ByteIOContext *pb, mkv_cues *cues)
281
{
282
    offset_t currentpos, cues_element;
283
    int i, j;
284

    
285
    currentpos = url_ftell(pb);
286
    cues_element = start_ebml_master(pb, MATROSKA_ID_CUES);
287

    
288
    for (i = 0; i < cues->num_entries; i++) {
289
        offset_t cuepoint, track_positions;
290
        mkv_cuepoint *entry = &cues->entries[i];
291
        uint64_t pts = entry->pts;
292

    
293
        cuepoint = start_ebml_master(pb, MATROSKA_ID_POINTENTRY);
294
        put_ebml_uint(pb, MATROSKA_ID_CUETIME, pts);
295

    
296
        // put all the entries from different tracks that have the exact same
297
        // timestamp into the same CuePoint
298
        for (j = 0; j < cues->num_entries - i && entry[j].pts == pts; j++) {
299
            track_positions = start_ebml_master(pb, MATROSKA_ID_CUETRACKPOSITION);
300
            put_ebml_uint(pb, MATROSKA_ID_CUETRACK          , entry[j].tracknum   );
301
            put_ebml_uint(pb, MATROSKA_ID_CUECLUSTERPOSITION, entry[j].cluster_pos);
302
            end_ebml_master(pb, track_positions);
303
        }
304
        i += j - 1;
305
        end_ebml_master(pb, cuepoint);
306
    }
307
    end_ebml_master(pb, cues_element);
308

    
309
    av_free(cues->entries);
310
    av_free(cues);
311
    return currentpos;
312
}
313

    
314
static int put_xiph_codecpriv(ByteIOContext *pb, AVCodecContext *codec)
315
{
316
    offset_t codecprivate;
317
    uint8_t *header_start[3];
318
    int header_len[3];
319
    int first_header_size;
320
    int j, k;
321

    
322
    if (codec->codec_id == CODEC_ID_VORBIS)
323
        first_header_size = 30;
324
    else
325
        first_header_size = 42;
326

    
327
    if (ff_split_xiph_headers(codec->extradata, codec->extradata_size,
328
                              first_header_size, header_start, header_len) < 0) {
329
        av_log(codec, AV_LOG_ERROR, "Extradata corrupt.\n");
330
        return -1;
331
    }
332

    
333
    codecprivate = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE);
334
    put_byte(pb, 2);                    // number packets - 1
335
    for (j = 0; j < 2; j++) {
336
        for (k = 0; k < header_len[j] / 255; k++)
337
            put_byte(pb, 255);
338
        put_byte(pb, header_len[j] % 255);
339
    }
340
    for (j = 0; j < 3; j++)
341
        put_buffer(pb, header_start[j], header_len[j]);
342
    end_ebml_master(pb, codecprivate);
343

    
344
    return 0;
345
}
346

    
347
static void get_aac_sample_rates(AVCodecContext *codec, int *sample_rate, int *output_sample_rate)
348
{
349
    static const int aac_sample_rates[] = {
350
        96000, 88200, 64000, 48000, 44100, 32000,
351
        24000, 22050, 16000, 12000, 11025,  8000,
352
    };
353
    int sri;
354

    
355
    if (codec->extradata_size < 2) {
356
        av_log(codec, AV_LOG_WARNING, "no aac extradata, unable to determine sample rate\n");
357
        return;
358
    }
359

    
360
    sri = ((codec->extradata[0] << 1) & 0xE) | (codec->extradata[1] >> 7);
361
    if (sri > 12) {
362
        av_log(codec, AV_LOG_WARNING, "aac samplerate index out of bounds\n");
363
        return;
364
    }
365
    *sample_rate = aac_sample_rates[sri];
366

    
367
    // if sbr, get output sample rate as well
368
    if (codec->extradata_size == 5) {
369
        sri = (codec->extradata[4] >> 3) & 0xF;
370
        if (sri > 12) {
371
            av_log(codec, AV_LOG_WARNING, "aac output samplerate index out of bounds\n");
372
            return;
373
        }
374
        *output_sample_rate = aac_sample_rates[sri];
375
    }
376
}
377

    
378
static int mkv_write_tracks(AVFormatContext *s)
379
{
380
    MatroskaMuxContext *mkv = s->priv_data;
381
    ByteIOContext *pb = &s->pb;
382
    offset_t tracks;
383
    int i, j;
384

    
385
    if (mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_TRACKS, url_ftell(pb)) < 0)
386
        return -1;
387

    
388
    tracks = start_ebml_master(pb, MATROSKA_ID_TRACKS);
389
    for (i = 0; i < s->nb_streams; i++) {
390
        AVStream *st = s->streams[i];
391
        AVCodecContext *codec = st->codec;
392
        offset_t subinfo, track;
393
        int native_id = 0;
394
        int bit_depth = av_get_bits_per_sample(codec->codec_id);
395
        int sample_rate = codec->sample_rate;
396
        int output_sample_rate = 0;
397

    
398
        if (codec->codec_id == CODEC_ID_AAC)
399
            get_aac_sample_rates(codec, &sample_rate, &output_sample_rate);
400

    
401
        track = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY);
402
        put_ebml_uint (pb, MATROSKA_ID_TRACKNUMBER     , i + 1);
403
        put_ebml_uint (pb, MATROSKA_ID_TRACKUID        , i + 1);
404
        put_ebml_uint (pb, MATROSKA_ID_TRACKFLAGLACING , 0);    // no lacing (yet)
405

    
406
        if (st->language[0])
407
            put_ebml_string(pb, MATROSKA_ID_TRACKLANGUAGE, st->language);
408

    
409
        // look for a codec id string specific to mkv to use, if none are found, use AVI codes
410
        for (j = 0; ff_mkv_codec_tags[j].id != CODEC_ID_NONE; j++) {
411
            if (ff_mkv_codec_tags[j].id == codec->codec_id) {
412
                put_ebml_string(pb, MATROSKA_ID_CODECID, ff_mkv_codec_tags[j].str);
413
                native_id = 1;
414
                break;
415
            }
416
        }
417

    
418
        // XXX: CodecPrivate for vorbis, theora, aac, native mpeg4, ...
419
        if (native_id) {
420
            if (codec->codec_id == CODEC_ID_VORBIS || codec->codec_id == CODEC_ID_THEORA) {
421
                if (put_xiph_codecpriv(pb, codec) < 0)
422
                    return -1;
423
            } else if (codec->extradata_size) {
424
                put_ebml_binary(pb, MATROSKA_ID_CODECPRIVATE, codec->extradata, codec->extradata_size);
425
            }
426
        }
427

    
428
        switch (codec->codec_type) {
429
            case CODEC_TYPE_VIDEO:
430
                put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_VIDEO);
431

    
432
                if (!native_id) {
433
                    offset_t bmp_header;
434
                    // if there is no mkv-specific codec id, use VFW mode
435
                    if (!codec->codec_tag)
436
                        codec->codec_tag = codec_get_tag(codec_bmp_tags, codec->codec_id);
437

    
438
                    put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC);
439
                    bmp_header = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE);
440
                    put_bmp_header(pb, codec, codec_bmp_tags, 0);
441
                    end_ebml_master(pb, bmp_header);
442
                }
443
                subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKVIDEO);
444
                // XXX: interlace flag?
445
                put_ebml_uint (pb, MATROSKA_ID_VIDEOPIXELWIDTH , codec->width);
446
                put_ebml_uint (pb, MATROSKA_ID_VIDEOPIXELHEIGHT, codec->height);
447
                // XXX: display width/height
448
                end_ebml_master(pb, subinfo);
449
                break;
450

    
451
            case CODEC_TYPE_AUDIO:
452
                put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_AUDIO);
453

    
454
                if (!native_id) {
455
                    offset_t wav_header;
456
                    // no mkv-specific ID, use ACM mode
457
                    codec->codec_tag = codec_get_tag(codec_wav_tags, codec->codec_id);
458
                    if (!codec->codec_tag) {
459
                        av_log(s, AV_LOG_ERROR, "no codec id found for stream %d", i);
460
                        return -1;
461
                    }
462

    
463
                    put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_AUDIO_ACM);
464
                    wav_header = start_ebml_master(pb, MATROSKA_ID_CODECPRIVATE);
465
                    put_wav_header(pb, codec);
466
                    end_ebml_master(pb, wav_header);
467
                }
468
                subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKAUDIO);
469
                put_ebml_uint  (pb, MATROSKA_ID_AUDIOCHANNELS    , codec->channels);
470
                put_ebml_float (pb, MATROSKA_ID_AUDIOSAMPLINGFREQ, sample_rate);
471
                if (output_sample_rate)
472
                    put_ebml_float(pb, MATROSKA_ID_AUDIOOUTSAMPLINGFREQ, output_sample_rate);
473
                if (bit_depth)
474
                    put_ebml_uint(pb, MATROSKA_ID_AUDIOBITDEPTH, bit_depth);
475
                end_ebml_master(pb, subinfo);
476
                break;
477

    
478
                case CODEC_TYPE_SUBTITLE:
479
                    put_ebml_uint(pb, MATROSKA_ID_TRACKTYPE, MATROSKA_TRACK_TYPE_SUBTITLE);
480
                    break;
481
            default:
482
                av_log(s, AV_LOG_ERROR, "Only audio and video are supported for Matroska.");
483
                break;
484
        }
485
        end_ebml_master(pb, track);
486

    
487
        // ms precision is the de-facto standard timescale for mkv files
488
        av_set_pts_info(st, 64, 1, 1000);
489
    }
490
    end_ebml_master(pb, tracks);
491
    return 0;
492
}
493

    
494
static int mkv_write_header(AVFormatContext *s)
495
{
496
    MatroskaMuxContext *mkv = s->priv_data;
497
    ByteIOContext *pb = &s->pb;
498
    offset_t ebml_header, segment_info;
499

    
500
    ebml_header = start_ebml_master(pb, EBML_ID_HEADER);
501
    put_ebml_uint   (pb, EBML_ID_EBMLVERSION        ,           1);
502
    put_ebml_uint   (pb, EBML_ID_EBMLREADVERSION    ,           1);
503
    put_ebml_uint   (pb, EBML_ID_EBMLMAXIDLENGTH    ,           4);
504
    put_ebml_uint   (pb, EBML_ID_EBMLMAXSIZELENGTH  ,           8);
505
    put_ebml_string (pb, EBML_ID_DOCTYPE            ,  "matroska");
506
    put_ebml_uint   (pb, EBML_ID_DOCTYPEVERSION     ,           2);
507
    put_ebml_uint   (pb, EBML_ID_DOCTYPEREADVERSION ,           2);
508
    end_ebml_master(pb, ebml_header);
509

    
510
    mkv->segment = start_ebml_master(pb, MATROSKA_ID_SEGMENT);
511
    mkv->segment_offset = url_ftell(pb);
512

    
513
    // we write 2 seek heads - one at the end of the file to point to each cluster, and
514
    // one at the beginning to point to all other level one elements (including the seek
515
    // head at the end of the file), which isn't more than 10 elements if we only write one
516
    // of each other currently defined level 1 element
517
    mkv->main_seekhead    = mkv_start_seekhead(pb, mkv->segment_offset, 10);
518
    mkv->cluster_seekhead = mkv_start_seekhead(pb, mkv->segment_offset, 0);
519

    
520
    if (mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_INFO, url_ftell(pb)) < 0)
521
        return -1;
522

    
523
    segment_info = start_ebml_master(pb, MATROSKA_ID_INFO);
524
    put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000);
525
    if (strlen(s->title))
526
        put_ebml_string(pb, MATROSKA_ID_TITLE, s->title);
527
    if (!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) {
528
        put_ebml_string(pb, MATROSKA_ID_MUXINGAPP, LIBAVFORMAT_IDENT);
529
        // XXX: both are required; something better for writing app?
530
        put_ebml_string(pb, MATROSKA_ID_WRITINGAPP, LIBAVFORMAT_IDENT);
531
    }
532
    // XXX: segment UID
533
    // reserve space for the duration
534
    mkv->duration = 0;
535
    mkv->duration_offset = url_ftell(pb);
536
    put_ebml_void(pb, 11);                  // assumes double-precision float to be written
537
    end_ebml_master(pb, segment_info);
538

    
539
    if (mkv_write_tracks(s) < 0)
540
        return -1;
541

    
542
    if (mkv_add_seekhead_entry(mkv->cluster_seekhead, MATROSKA_ID_CLUSTER, url_ftell(pb)) < 0)
543
        return -1;
544

    
545
    mkv->cluster_pos = url_ftell(pb);
546
    mkv->cluster = start_ebml_master(pb, MATROSKA_ID_CLUSTER);
547
    put_ebml_uint(pb, MATROSKA_ID_CLUSTERTIMECODE, 0);
548
    mkv->cluster_pts = 0;
549

    
550
    mkv->cues = mkv_start_cues(mkv->segment_offset);
551
    if (mkv->cues == NULL)
552
        return -1;
553

    
554
    return 0;
555
}
556

    
557
static void mkv_write_block(AVFormatContext *s, unsigned int blockid, AVPacket *pkt, int flags)
558
{
559
    MatroskaMuxContext *mkv = s->priv_data;
560
    ByteIOContext *pb = &s->pb;
561

    
562
    put_ebml_id(pb, blockid);
563
    put_ebml_size(pb, pkt->size + 4, 0);
564
    put_byte(pb, 0x80 | (pkt->stream_index + 1));     // this assumes stream_index is less than 126
565
    put_be16(pb, pkt->pts - mkv->cluster_pts);
566
    put_byte(pb, flags);
567
    put_buffer(pb, pkt->data, pkt->size);
568
}
569

    
570
static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
571
{
572
    MatroskaMuxContext *mkv = s->priv_data;
573
    ByteIOContext *pb = &s->pb;
574
    int keyframe = !!(pkt->flags & PKT_FLAG_KEY);
575

    
576
    // start a new cluster every 5 MB or 5 sec
577
    if (url_ftell(pb) > mkv->cluster + 5*1024*1024 || pkt->pts > mkv->cluster_pts + 5000) {
578
        end_ebml_master(pb, mkv->cluster);
579

    
580
        if (mkv_add_seekhead_entry(mkv->cluster_seekhead, MATROSKA_ID_CLUSTER, url_ftell(pb)) < 0)
581
            return -1;
582

    
583
        mkv->cluster_pos = url_ftell(pb);
584
        mkv->cluster = start_ebml_master(pb, MATROSKA_ID_CLUSTER);
585
        put_ebml_uint(pb, MATROSKA_ID_CLUSTERTIMECODE, pkt->pts);
586
        mkv->cluster_pts = pkt->pts;
587
    }
588

    
589
    if (s->streams[pkt->stream_index]->codec->codec_type != CODEC_TYPE_SUBTITLE) {
590
    mkv_write_block(s, MATROSKA_ID_SIMPLEBLOCK, pkt, keyframe << 7);
591
    } else {
592
        offset_t blockgroup = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP);
593
        mkv_write_block(s, MATROSKA_ID_BLOCK, pkt, 0);
594
        put_ebml_uint(pb, MATROSKA_ID_DURATION, pkt->duration);
595
        end_ebml_master(pb, blockgroup);
596
    }
597

    
598
    if (s->streams[pkt->stream_index]->codec->codec_type == CODEC_TYPE_VIDEO && keyframe) {
599
        if (mkv_add_cuepoint(mkv->cues, pkt, mkv->cluster_pos) < 0)
600
            return -1;
601
    }
602

    
603
    mkv->duration = pkt->pts + pkt->duration;
604
    return 0;
605
}
606

    
607
static int mkv_write_trailer(AVFormatContext *s)
608
{
609
    MatroskaMuxContext *mkv = s->priv_data;
610
    ByteIOContext *pb = &s->pb;
611
    offset_t currentpos, second_seekhead, cuespos;
612

    
613
    end_ebml_master(pb, mkv->cluster);
614

    
615
    cuespos = mkv_write_cues(pb, mkv->cues);
616
    second_seekhead = mkv_write_seekhead(pb, mkv->cluster_seekhead);
617

    
618
    mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CUES    , cuespos);
619
    mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_SEEKHEAD, second_seekhead);
620
    mkv_write_seekhead(pb, mkv->main_seekhead);
621

    
622
    // update the duration
623
    currentpos = url_ftell(pb);
624
    url_fseek(pb, mkv->duration_offset, SEEK_SET);
625
    put_ebml_float(pb, MATROSKA_ID_DURATION, mkv->duration);
626
    url_fseek(pb, currentpos, SEEK_SET);
627

    
628
    end_ebml_master(pb, mkv->segment);
629
    return 0;
630
}
631

    
632
AVOutputFormat matroska_muxer = {
633
    "matroska",
634
    "Matroska File Format",
635
    "video/x-matroska",
636
    "mkv",
637
    sizeof(MatroskaMuxContext),
638
    CODEC_ID_MP2,
639
    CODEC_ID_MPEG4,
640
    mkv_write_header,
641
    mkv_write_packet,
642
    mkv_write_trailer,
643
    .codec_tag = (const AVCodecTag*[]){codec_bmp_tags, codec_wav_tags, 0},
644
};