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transcoding: handle change of audio format 
Note, that this also introduces an audio encoder behavioural change. Before, if the number of input channels was lower than the audio channels setting, the input channel number was used instead of the setting. Now, if the number of input channels is lower, the audio is upmixed to the configured number of channels, as the number of channels of the input may change to be the same as the audio channels setting.
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@stbenz @perexg
stbenz authored and perexg committed Jun 8, 2015
1 parent cdbb459 commit b7cce6a
Showing 1 changed file with 56 additions and 30 deletions.
86 changes: 56 additions & 30 deletions src/plumbing/transcoding.c
View file
Expand Up @@ -76,6 +76,10 @@ typedef struct audio_stream {
int resample;
int resample_is_open;

enum AVSampleFormat last_sample_fmt;
int last_sample_rate;
uint64_t last_channel_layout;

} audio_stream_t;


Expand Down Expand Up @@ -471,6 +475,7 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
audio_stream_t *as = (audio_stream_t*)ts;
int got_frame, got_packet_ptr;
AVFrame *frame = av_frame_alloc();
char layout_buf[100];

ictx = as->aud_ictx;
octx = as->aud_octx;
Expand Down Expand Up @@ -546,7 +551,7 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
octx->sample_rate = transcode_get_sample_rate(ictx->sample_rate, ocodec);
octx->sample_fmt = transcode_get_sample_fmt(ictx->sample_fmt, ocodec);
octx->time_base = ictx->time_base;
octx->channels = as->aud_channels ? MIN(as->aud_channels, ictx->channels) : ictx->channels;
octx->channels = as->aud_channels ? as->aud_channels : ictx->channels;
octx->channel_layout = transcode_get_channel_layout(&octx->channels, ocodec);
octx->bit_rate = as->aud_bitrate ? as->aud_bitrate : 0;
octx->flags |= CODEC_FLAG_GLOBAL_HEADER;
Expand Down Expand Up @@ -574,7 +579,6 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
transcoder_stream_invalidate(ts);
goto cleanup;
} else {
char layout_buf[100];
av_get_channel_layout_string(layout_buf, sizeof (layout_buf), octx->channels, octx->channel_layout);
tvhdebug("transcode", "%04X: using audio channel layout %s",
shortid(t), layout_buf);
Expand Down Expand Up @@ -619,11 +623,6 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
break;
}

as->resample = (ictx->channels != octx->channels) ||
(ictx->channel_layout != octx->channel_layout) ||
(ictx->sample_fmt != octx->sample_fmt) ||
(ictx->sample_rate != octx->sample_rate);

octx->codec_id = ocodec->id;

if (avcodec_open2(octx, ocodec, NULL) < 0) {
Expand All @@ -633,23 +632,62 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
goto cleanup;
}

as->resample_context = NULL;
if (as->resample) {
as->fifo = av_audio_fifo_alloc(octx->sample_fmt, octx->channels, 1);
if (!as->fifo) {
tvherror("transcode", "%04X: Could not allocate fifo", shortid(t));
transcoder_stream_invalidate(ts);
goto cleanup;
}

as->resample_context = NULL;

as->last_sample_rate = ictx->sample_rate;
as->last_sample_fmt = ictx->sample_fmt;
as->last_channel_layout = ictx->channel_layout;
}

/* check for changed input format and close resampler, if changed */
if (as->last_sample_rate != ictx->sample_rate ||
as->last_sample_fmt != ictx->sample_fmt ||
as->last_channel_layout != ictx->channel_layout) {
tvhdebug("transcode", "%04X: audio input format changed", shortid(t));

as->last_sample_rate = ictx->sample_rate;
as->last_sample_fmt = ictx->sample_fmt;
as->last_channel_layout = ictx->channel_layout;

if (as->resample_context) {
tvhdebug("transcode", "%04X: stopping audio resampling", shortid(t));
avresample_free(&as->resample_context);
as->resample_context = NULL;
as->resample_is_open = 0;
}
}

as->resample = (ictx->channel_layout != octx->channel_layout) ||
(ictx->sample_fmt != octx->sample_fmt) ||
(ictx->sample_rate != octx->sample_rate);

if (as->resample) {
if (!as->resample_context) {
if (!(as->resample_context = avresample_alloc_context())) {
tvherror("transcode", "%04X: Could not allocate resample context", shortid(t));
transcoder_stream_invalidate(ts);
goto cleanup;
}

// Convert audio
tvhtrace("transcode", "%04X: converting audio", shortid(t));
// resample audio
tvhdebug("transcode", "%04X: starting audio resampling", shortid(t));

av_get_channel_layout_string(layout_buf, sizeof (layout_buf), ictx->channels, ictx->channel_layout);
tvhdebug("transcode", "%04X: IN : channel_layout=%s, rate=%d, fmt=%s, bitrate=%d",
shortid(t), layout_buf, ictx->sample_rate,
av_get_sample_fmt_name(ictx->sample_fmt), ictx->bit_rate);

tvhtrace("transcode", "%04X: IN : channels=%d, layout=%" PRIi64 ", rate=%d, fmt=%d, bitrate=%d",
shortid(t), ictx->channels, ictx->channel_layout, ictx->sample_rate,
ictx->sample_fmt, ictx->bit_rate);
tvhtrace("transcode", "%04X: OUT: channels=%d, layout=%" PRIi64 ", rate=%d, fmt=%d, bitrate=%d",
shortid(t), octx->channels, octx->channel_layout, octx->sample_rate,
octx->sample_fmt, octx->bit_rate);
av_get_channel_layout_string(layout_buf, sizeof (layout_buf), octx->channels, octx->channel_layout);
tvhdebug("transcode", "%04X: OUT: channel_layout=%s, rate=%d, fmt=%s, bitrate=%d",
shortid(t), layout_buf, octx->sample_rate,
av_get_sample_fmt_name(octx->sample_fmt), octx->bit_rate);

if (transcode_opt_set_int(t, ts, as->resample_context,
"in_channel_layout", ictx->channel_layout, 1))
Expand All @@ -675,20 +713,8 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
goto cleanup;
}
as->resample_is_open = 1;

}

as->fifo = av_audio_fifo_alloc(octx->sample_fmt, octx->channels, 1);
if (!as->fifo) {
tvherror("transcode", "%04X: Could not allocate fifo", shortid(t));
transcoder_stream_invalidate(ts);
goto cleanup;
}

}

if (as->resample) {

uint8_t **output = alloca(octx->channels * sizeof(uint8_t *));

if (av_samples_alloc(output, NULL, octx->channels, frame->nb_samples, octx->sample_fmt, 1) < 0) {
Expand Down Expand Up @@ -818,7 +844,7 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
create_adts_header(n->pkt_payload, n->pkt_sri, octx->channels);

if (octx->extradata_size)
n->pkt_meta = pktbuf_alloc(octx->extradata, octx->extradata_size);
n->pkt_meta = pktbuf_alloc(octx->extradata, octx->extradata_size);

tvhtrace("transcode", "%04X: deliver audio (pts = %" PRIi64 ", delay = %i)",
shortid(t), n->pkt_pts, octx->delay);
Expand Down

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