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Code Issues Releases Activity

avformat/matroskadec: add WebVTT support

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WebM files now support inband text tracks, as described in the
following specification:

http://wiki.webmproject.org/webm-metadata/temporal-metadata/webvtt-in-webm

The Matroska demuxer now detects the presence of WebVTT tracks,
synthesizing WebVTT packets (having codec id AV_CODEC_ID_WEBVTT) and
pushing them downstream in the normal way.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Matthew Heaney 2013-08-08 15:40:03 -07:00 committed by Michael Niedermayer
parent 23b3141261
commit 818ebe930f
3 changed files with 140 additions and 2 deletions
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5
libavformat/matroska.c
View File

@ -57,6 +57,11 @@ const CodecTags ff_mkv_codec_tags[]={
{"A_VORBIS" , AV_CODEC_ID_VORBIS},
{"A_WAVPACK4" , AV_CODEC_ID_WAVPACK},
{"D_WEBVTT/SUBTITLES" , AV_CODEC_ID_WEBVTT},
{"D_WEBVTT/CAPTIONS" , AV_CODEC_ID_WEBVTT},
{"D_WEBVTT/DESCRIPTIONS", AV_CODEC_ID_WEBVTT},
{"D_WEBVTT/METADATA" , AV_CODEC_ID_WEBVTT},
{"S_TEXT/UTF8" , AV_CODEC_ID_SUBRIP},
{"S_TEXT/UTF8" , AV_CODEC_ID_TEXT},
{"S_TEXT/UTF8" , AV_CODEC_ID_SRT},

2
libavformat/matroska.h
View File

@ -265,7 +265,7 @@ typedef enum {
*/
typedef struct CodecTags{
char str[20];
char str[22];
enum AVCodecID id;
}CodecTags;

135
libavformat/matroskadec.c
View File

@ -1566,7 +1566,8 @@ static int matroska_read_header(AVFormatContext *s)
/* Apply some sanity checks. */
if (track->type != MATROSKA_TRACK_TYPE_VIDEO &&
track->type != MATROSKA_TRACK_TYPE_AUDIO &&
track->type != MATROSKA_TRACK_TYPE_SUBTITLE) {
track->type != MATROSKA_TRACK_TYPE_SUBTITLE &&
track->type != MATROSKA_TRACK_TYPE_METADATA) {
av_log(matroska->ctx, AV_LOG_INFO,
"Unknown or unsupported track type %"PRIu64"\n",
track->type);
@ -1862,6 +1863,16 @@ static int matroska_read_header(AVFormatContext *s)
st->codec->bits_per_coded_sample = track->audio.bitdepth;
if (st->codec->codec_id != AV_CODEC_ID_AAC)
st->need_parsing = AVSTREAM_PARSE_HEADERS;
} else if (codec_id == AV_CODEC_ID_WEBVTT) {
st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
if (!strcmp(track->codec_id, "D_WEBVTT/CAPTIONS")) {
st->disposition |= AV_DISPOSITION_CAPTIONS;
} else if (!strcmp(track->codec_id, "D_WEBVTT/DESCRIPTIONS")) {
st->disposition |= AV_DISPOSITION_DESCRIPTIONS;
} else if (!strcmp(track->codec_id, "D_WEBVTT/METADATA")) {
st->disposition |= AV_DISPOSITION_METADATA;
}
} else if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE) {
st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
#if FF_API_ASS_SSA
@ -2228,6 +2239,120 @@ fail:
return ret;
}
static int matroska_parse_webvtt(MatroskaDemuxContext *matroska,
MatroskaTrack *track,
AVStream *st,
uint8_t *data, int data_len,
uint64_t timecode,
uint64_t duration,
int64_t pos)
{
AVPacket *pkt;
uint8_t *id, *settings, *text, *buf;
int id_len, settings_len, text_len;
uint8_t *p, *q;
int err;
if (data_len <= 0)
return AVERROR_INVALIDDATA;
p = data;
q = data + data_len;
id = p;
id_len = -1;
while (p < q) {
if (*p == '\r' || *p == '\n') {
id_len = p - id;
if (*p == '\r')
p++;
break;
}
p++;
}
if (p >= q || *p != '\n')
return AVERROR_INVALIDDATA;
p++;
settings = p;
settings_len = -1;
while (p < q) {
if (*p == '\r' || *p == '\n') {
settings_len = p - settings;
if (*p == '\r')
p++;
break;
}
p++;
}
if (p >= q || *p != '\n')
return AVERROR_INVALIDDATA;
p++;
text = p;
text_len = q - p;
while (text_len > 0) {
const int len = text_len - 1;
const uint8_t c = p[len];
if (c != '\r' && c != '\n')
break;
text_len = len;
}
if (text_len <= 0)
return AVERROR_INVALIDDATA;
pkt = av_mallocz(sizeof(*pkt));
err = av_new_packet(pkt, text_len);
if (err < 0) {
av_free(pkt);
return AVERROR(err);
}
memcpy(pkt->data, text, text_len);
if (id_len > 0) {
buf = av_packet_new_side_data(pkt,
AV_PKT_DATA_WEBVTT_IDENTIFIER,
id_len);
if (buf == NULL) {
av_free(pkt);
return AVERROR(ENOMEM);
}
memcpy(buf, id, id_len);
}
if (settings_len > 0) {
buf = av_packet_new_side_data(pkt,
AV_PKT_DATA_WEBVTT_SETTINGS,
settings_len);
if (buf == NULL) {
av_free(pkt);
return AVERROR(ENOMEM);
}
memcpy(buf, settings, settings_len);
}
// Do we need this for subtitles?
// pkt->flags = AV_PKT_FLAG_KEY;
pkt->stream_index = st->index;
pkt->pts = timecode;
// Do we need this for subtitles?
// pkt->dts = timecode;
pkt->duration = duration;
pkt->pos = pos;
dynarray_add(&matroska->packets, &matroska->num_packets, pkt);
matroska->prev_pkt = pkt;
return 0;
}
static int matroska_parse_frame(MatroskaDemuxContext *matroska,
MatroskaTrack *track,
AVStream *st,
@ -2456,6 +2581,14 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
if (res)
goto end;
} else if (st->codec->codec_id == AV_CODEC_ID_WEBVTT) {
res = matroska_parse_webvtt(matroska, track, st,
data, lace_size[n],
timecode, lace_duration,
pos);
if (res)
goto end;
} else {
res = matroska_parse_frame(matroska, track, st, data, lace_size[n],
timecode, lace_duration,