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mp3enc: write Xing TOC

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Based on the code by:
Peter Belkner <pbelkner@snafu.de>,
Michael Niedermayer <michaelni@gmx.at>,
Clément Bœsch <clement.boesch@smartjog.com>,
Reimar Döffinger <Reimar.Doeffinger@gmx.de>, and
Tobias Rapp <t.rapp@noa-audio.com>
Alex Converse <alex.converse@gmail.com>

Signed-off-by: Anton Khirnov <anton@khirnov.net>
pull/28/head
Anton Khirnov 12 years ago
parent ca8e39dd0d
commit 7040c9fac2
1 changed files with 120 additions and 20 deletions
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  1. 140
      libavformat/mp3enc.c

140
libavformat/mp3enc.c
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@ -74,12 +74,27 @@ static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
return count;
}
#define XING_NUM_BAGS 400
#define XING_TOC_SIZE 100
// maximum size of the xing frame: offset/Xing/flags/frames/size/TOC
#define XING_MAX_SIZE (32 + 4 + 4 + 4 + 4 + XING_TOC_SIZE)
typedef struct MP3Context {
const AVClass *class;
ID3v2EncContext id3;
int id3v2_version;
int write_id3v1;
int64_t nb_frames_offset;
/* xing header */
int64_t xing_offset;
int32_t frames;
int32_t size;
uint32_t want;
uint32_t seen;
uint32_t pos;
uint64_t bag[XING_NUM_BAGS];
int initial_bitrate;
int has_variable_bitrate;
/* index of the audio stream */
int audio_stream_idx;
@ -92,15 +107,17 @@ typedef struct MP3Context {
static const uint8_t xing_offtbl[2][2] = {{32, 17}, {17, 9}};
/* insert a dummy frame containing number of frames */
/*
* Write an empty XING header and initialize respective data.
*/
static void mp3_write_xing(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec;
int bitrate_idx = 1; // 32 kbps
int32_t header;
MPADecodeHeader mpah;
int srate_idx, i, channels;
int bitrate_idx;
int xing_offset;
int ver = 0;
@ -132,6 +149,9 @@ static void mp3_write_xing(AVFormatContext *s)
return;
}
/* 64 kbps frame, should be large enough */
bitrate_idx = (ver == 3) ? 5 : 8;
/* dummy MPEG audio header */
header = 0xff << 24; // sync
header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/
@ -141,17 +161,78 @@ static void mp3_write_xing(AVFormatContext *s)
avpriv_mpegaudio_decode_header(&mpah, header);
av_assert0(mpah.frame_size >= XING_MAX_SIZE);
xing_offset = xing_offtbl[ver != 3][codec->channels == 1];
ffio_fill(s->pb, 0, xing_offset);
mp3->xing_offset = avio_tell(s->pb);
ffio_wfourcc(s->pb, "Xing");
avio_wb32(s->pb, 0x1); // only number of frames
mp3->nb_frames_offset = avio_tell(s->pb);
avio_wb32(s->pb, 0);
avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC
mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
mp3->size = mpah.frame_size;
mp3->want = 1;
avio_wb32(s->pb, 0); // frames
avio_wb32(s->pb, 0); // size
// TOC
for (i = 0; i < XING_TOC_SIZE; i++)
avio_w8(s->pb, 255 * i / XING_TOC_SIZE);
mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4 + 4 + XING_TOC_SIZE;
ffio_fill(s->pb, 0, mpah.frame_size);
}
/*
* Add a frame to XING data.
* Following lame's "VbrTag.c".
*/
static void mp3_xing_add_frame(MP3Context *mp3, AVPacket *pkt)
{
int i;
mp3->frames++;
mp3->seen++;
mp3->size += pkt->size;
if (mp3->want == mp3->seen) {
mp3->bag[mp3->pos] = mp3->size;
if (XING_NUM_BAGS == ++mp3->pos) {
/* shrink table to half size by throwing away each second bag. */
for (i = 1; i < XING_NUM_BAGS; i += 2)
mp3->bag[i / 2] = mp3->bag[i];
/* double wanted amount per bag. */
mp3->want *= 2;
/* adjust current position to half of table size. */
mp3->pos = XING_NUM_BAGS / 2;
}
mp3->seen = 0;
}
}
static int mp3_write_audio_packet(AVFormatContext *s, AVPacket *pkt)
{
MP3Context *mp3 = s->priv_data;
if (mp3->xing_offset && pkt->size >= 4) {
MPADecodeHeader c;
avpriv_mpegaudio_decode_header(&c, AV_RB32(pkt->data));
if (!mp3->initial_bitrate)
mp3->initial_bitrate = c.bit_rate;
if ((c.bit_rate == 0) || (mp3->initial_bitrate != c.bit_rate))
mp3->has_variable_bitrate = 1;
mp3_xing_add_frame(mp3, pkt);
}
return ff_raw_write_packet(s, pkt);
}
static int mp3_queue_flush(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
@ -162,7 +243,7 @@ static int mp3_queue_flush(AVFormatContext *s)
mp3_write_xing(s);
while ((pktl = mp3->queue)) {
if (write && (ret = ff_raw_write_packet(s, &pktl->pkt)) < 0)
if (write && (ret = mp3_write_audio_packet(s, &pktl->pkt)) < 0)
write = 0;
av_free_packet(&pktl->pkt);
mp3->queue = pktl->next;
@ -172,30 +253,50 @@ static int mp3_queue_flush(AVFormatContext *s)
return ret;
}
static void mp3_update_xing(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
int i;
/* replace "Xing" identification string with "Info" for CBR files. */
if (!mp3->has_variable_bitrate) {
avio_seek(s->pb, mp3->xing_offset, SEEK_SET);
ffio_wfourcc(s->pb, "Info");
}
avio_seek(s->pb, mp3->xing_offset + 8, SEEK_SET);
avio_wb32(s->pb, mp3->frames);
avio_wb32(s->pb, mp3->size);
avio_w8(s->pb, 0); // first toc entry has to be zero.
for (i = 1; i < XING_TOC_SIZE; ++i) {
int j = i * mp3->pos / XING_TOC_SIZE;
int seek_point = 256LL * mp3->bag[j] / mp3->size;
avio_w8(s->pb, FFMIN(seek_point, 255));
}
avio_seek(s->pb, 0, SEEK_END);
}
static int mp3_write_trailer(struct AVFormatContext *s)
{
uint8_t buf[ID3v1_TAG_SIZE];
MP3Context *mp3 = s->priv_data;
if (mp3 && mp3->pics_to_write) {
if (mp3->pics_to_write) {
av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
"attached pictures.\n");
mp3_queue_flush(s);
}
/* write the id3v1 tag */
if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
if (mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
avio_write(s->pb, buf, ID3v1_TAG_SIZE);
}
/* write number of frames */
if (mp3 && mp3->nb_frames_offset) {
avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
avio_wb32(s->pb, s->streams[mp3->audio_stream_idx]->nb_frames);
avio_seek(s->pb, 0, SEEK_END);
}
avio_flush(s->pb);
if (mp3->xing_offset)
mp3_update_xing(s);
return 0;
}
@ -209,7 +310,6 @@ AVOutputFormat ff_mp2_muxer = {
.audio_codec = AV_CODEC_ID_MP2,
.video_codec = AV_CODEC_ID_NONE,
.write_packet = ff_raw_write_packet,
.write_trailer = mp3_write_trailer,
.flags = AVFMT_NOTIMESTAMPS,
};
#endif
@ -251,7 +351,7 @@ static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt)
mp3->queue = pktl;
mp3->queue_end = pktl;
} else
return ff_raw_write_packet(s, pkt);
return mp3_write_audio_packet(s, pkt);
} else {
int ret;

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