77
#define XING_NUM_BAGS 400
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#define XING_TOC_SIZE 100
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// maximum size of the xing frame: offset/Xing/flags/frames/size/TOC
80
#define XING_MAX_SIZE (32 + 4 + 4 + 4 + 4 + XING_TOC_SIZE)
76
82
typedef struct MP3Context {
77
83
const AVClass *class;
80
int64_t nb_frames_offset;
95
uint64_t bag[XING_NUM_BAGS];
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int has_variable_bitrate;
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/* index of the audio stream */
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int audio_stream_idx;
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/* number of attached pictures we still need to write */
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/* audio packets are queued here until we get all the attached pictures */
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AVPacketList *queue, *queue_end;
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static const uint8_t xing_offtbl[2][2] = {{32, 17}, {17, 9}};
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* Write an empty XING header and initialize respective data.
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static void mp3_write_xing(AVFormatContext *s)
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MP3Context *mp3 = s->priv_data;
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AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec;
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MPADecodeHeader mpah;
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int srate_idx, i, channels;
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if (!s->pb->seekable)
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for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++) {
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const uint16_t base_freq = avpriv_mpa_freq_tab[i];
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if (codec->sample_rate == base_freq) ver = 0x3; // MPEG 1
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else if (codec->sample_rate == base_freq / 2) ver = 0x2; // MPEG 2
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else if (codec->sample_rate == base_freq / 4) ver = 0x0; // MPEG 2.5
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if (i == FF_ARRAY_ELEMS(avpriv_mpa_freq_tab)) {
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av_log(s, AV_LOG_WARNING, "Unsupported sample rate, not writing Xing "
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switch (codec->channels) {
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case 1: channels = MPA_MONO; break;
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case 2: channels = MPA_STEREO; break;
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default: av_log(s, AV_LOG_WARNING, "Unsupported number of channels, "
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"not writing Xing header.\n");
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/* 64 kbps frame, should be large enough */
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bitrate_idx = (ver == 3) ? 5 : 8;
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/* dummy MPEG audio header */
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header = 0xff << 24; // sync
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header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/
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header |= (bitrate_idx << 4 | srate_idx << 2) << 8;
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header |= channels << 6;
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avio_wb32(s->pb, header);
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avpriv_mpegaudio_decode_header(&mpah, header);
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av_assert0(mpah.frame_size >= XING_MAX_SIZE);
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xing_offset = xing_offtbl[ver != 3][codec->channels == 1];
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ffio_fill(s->pb, 0, xing_offset);
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mp3->xing_offset = avio_tell(s->pb);
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ffio_wfourcc(s->pb, "Xing");
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avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC
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mp3->size = mpah.frame_size;
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avio_wb32(s->pb, 0); // frames
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avio_wb32(s->pb, 0); // size
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for (i = 0; i < XING_TOC_SIZE; i++)
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avio_w8(s->pb, 255 * i / XING_TOC_SIZE);
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mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4 + 4 + XING_TOC_SIZE;
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ffio_fill(s->pb, 0, mpah.frame_size);
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* Add a frame to XING data.
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* Following lame's "VbrTag.c".
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static void mp3_xing_add_frame(MP3Context *mp3, AVPacket *pkt)
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mp3->size += pkt->size;
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if (mp3->want == mp3->seen) {
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mp3->bag[mp3->pos] = mp3->size;
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if (XING_NUM_BAGS == ++mp3->pos) {
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/* shrink table to half size by throwing away each second bag. */
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for (i = 1; i < XING_NUM_BAGS; i += 2)
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mp3->bag[i / 2] = mp3->bag[i];
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/* double wanted amount per bag. */
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/* adjust current position to half of table size. */
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mp3->pos = XING_NUM_BAGS / 2;
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static int mp3_write_audio_packet(AVFormatContext *s, AVPacket *pkt)
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MP3Context *mp3 = s->priv_data;
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if (mp3->xing_offset && pkt->size >= 4) {
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avpriv_mpegaudio_decode_header(&c, AV_RB32(pkt->data));
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if (!mp3->initial_bitrate)
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mp3->initial_bitrate = c.bit_rate;
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if ((c.bit_rate == 0) || (mp3->initial_bitrate != c.bit_rate))
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mp3->has_variable_bitrate = 1;
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mp3_xing_add_frame(mp3, pkt);
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return ff_raw_write_packet(s, pkt);
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static int mp3_queue_flush(AVFormatContext *s)
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MP3Context *mp3 = s->priv_data;
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int ret = 0, write = 1;
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ff_id3v2_finish(&mp3->id3, s->pb);
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while ((pktl = mp3->queue)) {
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if (write && (ret = mp3_write_audio_packet(s, &pktl->pkt)) < 0)
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av_free_packet(&pktl->pkt);
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mp3->queue = pktl->next;
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mp3->queue_end = NULL;
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static void mp3_update_xing(AVFormatContext *s)
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MP3Context *mp3 = s->priv_data;
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/* replace "Xing" identification string with "Info" for CBR files. */
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if (!mp3->has_variable_bitrate) {
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avio_seek(s->pb, mp3->xing_offset, SEEK_SET);
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ffio_wfourcc(s->pb, "Info");
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avio_seek(s->pb, mp3->xing_offset + 8, SEEK_SET);
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avio_wb32(s->pb, mp3->frames);
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avio_wb32(s->pb, mp3->size);
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avio_w8(s->pb, 0); // first toc entry has to be zero.
273
for (i = 1; i < XING_TOC_SIZE; ++i) {
274
int j = i * mp3->pos / XING_TOC_SIZE;
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int seek_point = 256LL * mp3->bag[j] / mp3->size;
276
avio_w8(s->pb, FFMIN(seek_point, 255));
279
avio_seek(s->pb, 0, SEEK_END);
83
282
static int mp3_write_trailer(struct AVFormatContext *s)
85
284
uint8_t buf[ID3v1_TAG_SIZE];
86
285
MP3Context *mp3 = s->priv_data;
287
if (mp3->pics_to_write) {
288
av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
289
"attached pictures.\n");
88
293
/* write the id3v1 tag */
89
if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
294
if (mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
90
295
avio_write(s->pb, buf, ID3v1_TAG_SIZE);
93
/* write number of frames */
94
if (mp3 && mp3->nb_frames_offset) {
95
avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
96
avio_wb32(s->pb, s->streams[0]->nb_frames);
97
avio_seek(s->pb, 0, SEEK_END);
298
if (mp3->xing_offset)
132
331
.version = LIBAVUTIL_VERSION_INT,
135
/* insert a dummy frame containing number of frames */
136
static void mp3_write_xing(AVFormatContext *s)
334
static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt)
138
AVCodecContext *codec = s->streams[0]->codec;
139
MP3Context *mp3 = s->priv_data;
140
int bitrate_idx = 1; // 32 kbps
141
int64_t xing_offset = (codec->channels == 2) ? 32 : 17;
143
MPADecodeHeader mpah;
144
int srate_idx, i, channels;
146
for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++)
147
if (avpriv_mpa_freq_tab[i] == codec->sample_rate) {
336
MP3Context *mp3 = s->priv_data;
338
if (pkt->stream_index == mp3->audio_stream_idx) {
339
if (mp3->pics_to_write) {
340
/* buffer audio packets until we get all the pictures */
341
AVPacketList *pktl = av_mallocz(sizeof(*pktl));
343
return AVERROR(ENOMEM);
346
pkt->destruct = NULL;
349
mp3->queue_end->next = pktl;
352
mp3->queue_end = pktl;
354
return mp3_write_audio_packet(s, pkt);
358
/* warn only once for each stream */
359
if (s->streams[pkt->stream_index]->nb_frames == 1) {
360
av_log(s, AV_LOG_WARNING, "Got more than one picture in stream %d,"
361
" ignoring.\n", pkt->stream_index);
151
if (i == FF_ARRAY_ELEMS(avpriv_mpa_freq_tab)) {
152
av_log(s, AV_LOG_ERROR, "Unsupported sample rate.\n");
156
switch (codec->channels) {
157
case 1: channels = MPA_MONO; break;
158
case 2: channels = MPA_STEREO; break;
159
default: av_log(s, AV_LOG_ERROR, "Unsupported number of channels.\n"); return;
162
/* dummy MPEG audio header */
163
header = 0xff << 24; // sync
164
header |= (0x7 << 5 | 0x3 << 3 | 0x1 << 1 | 0x1) << 16; // sync/mpeg-1/layer 3/no crc*/
165
header |= (bitrate_idx << 4 | srate_idx << 2) << 8;
166
header |= channels << 6;
167
avio_wb32(s->pb, header);
169
avpriv_mpegaudio_decode_header(&mpah, header);
171
ffio_fill(s->pb, 0, xing_offset);
172
ffio_wfourcc(s->pb, "Xing");
173
avio_wb32(s->pb, 0x1); // only number of frames
174
mp3->nb_frames_offset = avio_tell(s->pb);
177
mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
178
ffio_fill(s->pb, 0, mpah.frame_size);
363
if (!mp3->pics_to_write || s->streams[pkt->stream_index]->nb_frames >= 1)
366
if ((ret = ff_id3v2_write_apic(s, &mp3->id3, pkt)) < 0)
368
mp3->pics_to_write--;
370
/* flush the buffered audio packets */
371
if (!mp3->pics_to_write &&
372
(ret = mp3_queue_flush(s)) < 0)
185
383
static int mp3_write_header(struct AVFormatContext *s)
187
385
MP3Context *mp3 = s->priv_data;
190
ret = ff_id3v2_write(s, mp3->id3v2_version, ID3v2_DEFAULT_MAGIC);
388
/* check the streams -- we want exactly one audio and arbitrary number of
389
* video (attached pictures) */
390
mp3->audio_stream_idx = -1;
391
for (i = 0; i < s->nb_streams; i++) {
392
AVStream *st = s->streams[i];
393
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
394
if (mp3->audio_stream_idx >= 0 || st->codec->codec_id != AV_CODEC_ID_MP3) {
395
av_log(s, AV_LOG_ERROR, "Invalid audio stream. Exactly one MP3 "
396
"audio stream is required.\n");
397
return AVERROR(EINVAL);
399
mp3->audio_stream_idx = i;
400
} else if (st->codec->codec_type != AVMEDIA_TYPE_VIDEO) {
401
av_log(s, AV_LOG_ERROR, "Only audio streams and pictures are allowed in MP3.\n");
402
return AVERROR(EINVAL);
405
if (mp3->audio_stream_idx < 0) {
406
av_log(s, AV_LOG_ERROR, "No audio stream present.\n");
407
return AVERROR(EINVAL);
409
mp3->pics_to_write = s->nb_streams - 1;
411
ff_id3v2_start(&mp3->id3, s->pb, mp3->id3v2_version, ID3v2_DEFAULT_MAGIC);
412
ret = ff_id3v2_write_metadata(s, &mp3->id3);
416
if (!mp3->pics_to_write) {
417
ff_id3v2_finish(&mp3->id3, s->pb);
195
418
mp3_write_xing(s);
200
424
AVOutputFormat ff_mp3_muxer = {
202
.long_name = NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
426
.long_name = NULL_IF_CONFIG_SMALL("MP3 (MPEG audio layer 3)"),
203
427
.mime_type = "audio/x-mpeg",
204
428
.extensions = "mp3",
205
429
.priv_data_size = sizeof(MP3Context),
206
.audio_codec = CODEC_ID_MP3,
207
.video_codec = CODEC_ID_NONE,
430
.audio_codec = AV_CODEC_ID_MP3,
431
.video_codec = AV_CODEC_ID_PNG,
208
432
.write_header = mp3_write_header,
209
.write_packet = ff_raw_write_packet,
433
.write_packet = mp3_write_packet,
210
434
.write_trailer = mp3_write_trailer,
211
435
.flags = AVFMT_NOTIMESTAMPS,
212
.priv_class = &mp3_muxer_class,
436
.priv_class = &mp3_muxer_class,