ffmpeg添加mpeg ts对pcm的支持

来源：互联网发布：java退格符处理编辑：程序博客网时间：2024/04/29 00:25

在mpegtsenc.c的mpegts_write_pmt函数中，switch(st->codec->codec_id)的case中，添加如下代码

case AV_CODEC_ID_PCM_MULAW:

stream_type = 0x91;

break;

case AV_CODEC_ID_PCM_ALAW:

stream_type = 0x90;

break;

注意该流的定义与mpeg.c中的es_type是一致的，实际上这是mpeg中对mulaw和alaw的流类型定义关键字。这个关键字在后面还需要写到流中，在mpegtsenc.c中查找

else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&

(st->codec->codec_id == AV_CODEC_ID_MP2 ||

st->codec->codec_id == AV_CODEC_ID_MP3 ||

st->codec->codec_id == AV_CODEC_ID_AAC)) {

改为

else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&

(st->codec->codec_id == AV_CODEC_ID_MP2 ||

st->codec->codec_id == AV_CODEC_ID_MP3 ||

st->codec->codec_id == AV_CODEC_ID_AAC ||

st->codec->codec_id == AV_CODEC_ID_PCM_MULAW ||

st->codec->codec_id == AV_CODEC_ID_PCM_ALAW)) {

这段代码是在写入音频流关键字的判断

解码部分需要修改mprgts.c，修改流类型定义如下

static const StreamType ISO_types[] = {
{ 0x01, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_MPEG2VIDEO },
{ 0x02, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_MPEG2VIDEO },
{ 0x03, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_MP3 },
{ 0x04, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_MP3 },
{ 0x0f, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AAC },
{ 0x10, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_MPEG4 },
/* Makito encoder sets stream type 0x11 for AAC,
* so auto-detect LOAS/LATM instead of hardcoding it. */
#if !CONFIG_LOAS_DEMUXER
{ 0x11, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AAC_LATM }, /* LATM syntax */
#endif
{ 0x1b, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_H264 },
{ 0x24, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_HEVC },
{ 0x42, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_CAVS },
{ 0xd1, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_DIRAC },
{ 0xea, AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_VC1 },
{ 0x90, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_ALAW },
{ 0x91, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_MULAW },
{ 0 },
};

static const StreamType HDMV_types[] = {
{ 0x80, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_BLURAY },
{ 0x81, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AC3 },
{ 0x82, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ 0x83, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_TRUEHD },
{ 0x84, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_EAC3 },
{ 0x85, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS }, /* DTS HD */
{ 0x86, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS }, /* DTS HD MASTER*/
{ 0xa1, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_EAC3 }, /* E-AC3 Secondary Audio */
{ 0xa2, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS }, /* DTS Express Secondary Audio */
{ 0x90, AVMEDIA_TYPE_SUBTITLE, AV_CODEC_ID_HDMV_PGS_SUBTITLE },
{ 0x91, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_MULAW },
{ 0 },
};

/* ATSC ? */
static const StreamType MISC_types[] = {
{ 0x81, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AC3 },
{ 0x8a, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ 0x90, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_ALAW },
{ 0x91, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_MULAW },
{ 0 },
};

static const StreamType REGD_types[] = {
{ MKTAG('d', 'r', 'a', 'c'), AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_DIRAC },
{ MKTAG('A', 'C', '-', '3'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AC3 },
{ MKTAG('A', 'L', 'A', 'W'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_ALAW},
{ MKTAG('U', 'L', 'A', 'W'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_MULAW},
{ MKTAG('B', 'S', 'S', 'D'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_S302M },
{ MKTAG('D', 'T', 'S', '1'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ MKTAG('D', 'T', 'S', '2'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ MKTAG('D', 'T', 'S', '3'), AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ MKTAG('H', 'E', 'V', 'C'), AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_HEVC },
{ MKTAG('K', 'L', 'V', 'A'), AVMEDIA_TYPE_DATA, AV_CODEC_ID_SMPTE_KLV },
{ MKTAG('V', 'C', '-', '1'), AVMEDIA_TYPE_VIDEO, AV_CODEC_ID_VC1 },
{ 0 },
};

static const StreamType METADATA_types[] = {
{ MKTAG('K','L','V','A'), AVMEDIA_TYPE_DATA, AV_CODEC_ID_SMPTE_KLV },
{ MKTAG('I','D','3',' '), AVMEDIA_TYPE_DATA, AV_CODEC_ID_TIMED_ID3 },
{ 0 },
};

/* descriptor present */
static const StreamType DESC_types[] = {
{ 0x6a, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_AC3 }, /* AC-3 descriptor */
{ 0x7a, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_EAC3 }, /* E-AC-3 descriptor */
{ 0x7b, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_DTS },
{ 0x56, AVMEDIA_TYPE_SUBTITLE, AV_CODEC_ID_DVB_TELETEXT },
{ 0x59, AVMEDIA_TYPE_SUBTITLE, AV_CODEC_ID_DVB_SUBTITLE }, /* subtitling descriptor */
{ 0x90, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_ALAW },
{ 0x91, AVMEDIA_TYPE_AUDIO, AV_CODEC_ID_PCM_MULAW },
{ 0 },
};

上面的红字部分是添加的内容，注意HDMV_types中已经有了0x90的定义。

修改定义后，还需要在对law格式音频设置声音参数，修改mpegts_find_stream_type函数如下：

static void mpegts_find_stream_type(AVStream *st,
uint32_t stream_type,
const StreamType *types)
{
if (avcodec_is_open(st->codec)) {
av_log(NULL, AV_LOG_DEBUG, "cannot set stream info, codec is open\n");
return;
}

for (; types->stream_type; types++)
if (stream_type == types->stream_type) {
st->codec->codec_type = types->codec_type;
st->codec->codec_id = types->codec_id;
if (st->codec->codec_id == AV_CODEC_ID_PCM_MULAW || st->codec->codec_id == AV_CODEC_ID_PCM_ALAW)
{
st->codec->channels = 1;
st->codec->channel_layout = AV_CH_LAYOUT_MONO;
st->codec->sample_rate = 8000;
}
st->request_probe = 0;
return;
}
}

红色部分是添加内容

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