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transcoding: optimized audio encoder settings
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@stbenz @perexg
stbenz authored and perexg committed May 23, 2015
1 parent e7522d0 commit cad671d
Showing 1 changed file with 100 additions and 49 deletions.
149 changes: 100 additions & 49 deletions src/plumbing/transcoding.c
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Expand Up @@ -415,11 +415,6 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
tvhtrace("transcode", "%04X: audio decode: consumed=%d size=%zu, got=%d, pts=%" PRIi64,
shortid(t), length, pktbuf_len(pkt->pkt_payload), got_frame, pkt->pkt_pts);

if (!got_frame) {
tvhtrace("transcode", "%04X: Did not have a full frame in the packet", shortid(t));
goto cleanup;
}

if (length < 0) {
if (length == AVERROR_INVALIDDATA) goto cleanup;
tvherror("transcode", "%04X: Unable to decode audio (%d, %s)",
Expand All @@ -428,36 +423,66 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
goto cleanup;
}

if (length != pktbuf_len(pkt->pkt_payload))
tvhtrace("transcode",
"%04X: undecoded data (in=%zu, consumed=%d)",
shortid(t), pktbuf_len(pkt->pkt_payload), length);

if (length == 0 || !got_frame) {
tvhtrace("transcode", "%04X: Not yet enough data for decoding", shortid(t));
if (!got_frame) {
tvhtrace("transcode", "%04X: Did not have a full frame in the packet", shortid(t));
goto cleanup;
}

if (length != pktbuf_len(pkt->pkt_payload))
tvhwarn("transcode",
"%04X: undecoded data (in=%zu, consumed=%d)",
shortid(t), pktbuf_len(pkt->pkt_payload), length);

if (octx->codec_id == AV_CODEC_ID_NONE) {
as->aud_enc_pts = pkt->pkt_pts;
octx->sample_rate = ictx->sample_rate;
octx->sample_fmt = ictx->sample_fmt;

if (ocodec->supported_samplerates) {
/* Find if we have a matching sample_rate */
int acount = 0;
octx->sample_rate = 0;
int sample_rate_alt = 0;
while ((octx->sample_rate == 0) && (ocodec->supported_samplerates[acount] > 0)) {
if (ocodec->supported_samplerates[acount] == ictx->sample_rate) {
octx->sample_rate = ictx->sample_rate;
break;
}
if (ocodec->supported_samplerates[acount] > sample_rate_alt &&
ocodec->supported_samplerates[acount] < ictx->sample_rate) {
sample_rate_alt = ocodec->supported_samplerates[acount];
}
acount++;
}
if (octx->sample_rate == 0) {
if (sample_rate_alt > 0) {
tvhtrace("transcode", "%04X: sample_rate not supported, using: %d",
shortid(t), sample_rate_alt);
octx->sample_rate = sample_rate_alt;
} else {
tvherror("transcode", "%04X: Encoder no sample_rate!!??", shortid(t));
transcoder_stream_invalidate(ts);
goto cleanup;
}
}
}

if (ocodec->sample_fmts) {
/* Find if we have a matching sample_fmt */
int acount = 0;
octx->sample_fmt = -1;
while ((octx->sample_fmt == -1) && (ocodec->sample_fmts[acount] > -1)) {
octx->sample_fmt = AV_SAMPLE_FMT_NONE;
while ((octx->sample_fmt == AV_SAMPLE_FMT_NONE) && (ocodec->sample_fmts[acount] > AV_SAMPLE_FMT_NONE)) {
if (ocodec->sample_fmts[acount] == ictx->sample_fmt) {
octx->sample_fmt = ictx->sample_fmt;
break;
}
acount++;
}
if (octx->sample_fmt == -1) {
if (octx->sample_fmt == AV_SAMPLE_FMT_NONE) {
if (acount > 0) {
tvhtrace("transcode", "%04X: No sample_fmt, using: %d",
shortid(t), ocodec->sample_fmts[acount-1]);
octx->sample_fmt = ocodec->sample_fmts[acount-1];
tvhtrace("transcode", "%04X: sample_fmt not supported, using: %d",
shortid(t), ocodec->sample_fmts[0]);
octx->sample_fmt = ocodec->sample_fmts[0];
} else {
tvherror("transcode", "%04X: Encoder no sample_fmt!!??", shortid(t));
transcoder_stream_invalidate(ts);
Expand All @@ -466,14 +491,11 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
}
}

octx->time_base.den = ictx->time_base.den;
octx->time_base.num = ictx->time_base.num;

octx->channels = as->aud_channels ? as->aud_channels : ictx->channels;
octx->bit_rate = as->aud_bitrate ? as->aud_bitrate : ictx->bit_rate;
octx->time_base = ictx->time_base;
octx->channels = as->aud_channels ? MIN(as->aud_channels, ictx->channels) : ictx->channels;
octx->bit_rate = as->aud_bitrate ? as->aud_bitrate : 0;
octx->flags |= CODEC_FLAG_GLOBAL_HEADER;

octx->channels = MIN(octx->channels, ictx->channels);
octx->bit_rate = MIN(octx->bit_rate, ictx->bit_rate);

switch (octx->channels) {
case 1:
Expand Down Expand Up @@ -513,27 +535,40 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
}

if (ocodec->channel_layouts) {
/* Find a matching channel_layout */
int acount = 0, maxchannels = 0, maxacount = 0;
int acount = 0;
uint64_t channel_layout = octx->channel_layout;
uint64_t channel_layout_def = av_get_default_channel_layout(octx->channels);
uint64_t channel_layout_alt = 0;
int channels_alt = 0;
/* check if requested layout is available and find best suited alternative layout */
octx->channel_layout = 0;
while ((octx->channel_layout == 0) && (ocodec->channel_layouts[acount] > 0)) {
if ((av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]) >= maxchannels) &&
(av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]) <= octx->channels)) {
maxchannels = av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]);
maxacount = acount;
if (ocodec->channel_layouts[acount] == channel_layout) {
octx->channel_layout = channel_layout;
break;
}
if (av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]) <= octx->channels) {
if (av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]) > channels_alt) {
channel_layout_alt = ocodec->channel_layouts[acount];
channels_alt = av_get_channel_layout_nb_channels(channel_layout_alt);
} else if (av_get_channel_layout_nb_channels(ocodec->channel_layouts[acount]) == channels_alt &&
channel_layout_alt == channel_layout_def) {
channel_layout_alt = channel_layout_def;
channels_alt = av_get_channel_layout_nb_channels(channel_layout_alt);
}
}
if (ocodec->channel_layouts[acount] == ictx->channel_layout)
octx->channel_layout = ictx->channel_layout;
acount++;
}

if (octx->channel_layout == 0) {
if (acount > 0) {
if (channel_layout_alt != 0) {
/* find next which has same or less channels than decoder. */
tvhtrace("transcode", "%04X: No channel_layout, using: %d with %d channels",
shortid(t), (int)ocodec->channel_layouts[maxacount], maxchannels);
octx->channel_layout = ocodec->channel_layouts[maxacount];
octx->channels = maxchannels;
char layout_buf[100];
av_get_channel_layout_string(layout_buf, sizeof (layout_buf), channels_alt, channel_layout_alt);
tvhtrace("transcode", "%04X: channel_layout not available, using: %s",
shortid(t), layout_buf);
octx->channel_layout = channel_layout_alt;
octx->channels = channels_alt;
} else {
tvherror("transcode", "%04X: Encoder no channel_layout!!??", shortid(t));
transcoder_stream_invalidate(ts);
Expand All @@ -542,23 +577,39 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
}
}

// User specified streaming profile audio bitrate limiter.
if (t->t_props.tp_abitrate >= 16) {
octx->bit_rate = t->t_props.tp_abitrate * 1000;
}

// Set flags and quality settings, if no bitrate was specified.
// The MPEG2 encoder only supports encoding with fixed bitrate.
// All AAC encoders should support encoding with fixed bitrate,
// but some don't support encoding with global_quality (vbr).
// All vorbis encoders support encoding with global_quality (vbr),
// but the built in vorbis encoder doesn't support fixed bitrate.
switch (ts->ts_type) {
case SCT_MPEG2AUDIO:
// use 96 kbit per channel as default
if (octx->bit_rate == 0) {
octx->bit_rate = octx->channels * 96000;
}
break;

case SCT_AAC:
octx->flags |= CODEC_FLAG_BITEXACT;
octx->flags |= CODEC_FLAG_BITEXACT;
// use 64 kbit per channel as default
if (octx->bit_rate == 0) {
octx->bit_rate = octx->channels * 64000;
}
break;

case SCT_VORBIS:
octx->flags |= CODEC_FLAG_QSCALE;
octx->flags |= CODEC_FLAG_GLOBAL_HEADER;
octx->global_quality = 4*FF_QP2LAMBDA;
// use vbr with quality setting as default
// and also use a user specified bitrate < 16 kbit as quality setting
if (octx->bit_rate == 0) {
octx->flags |= CODEC_FLAG_QSCALE;
octx->global_quality = 4 * FF_QP2LAMBDA;
} else if (t->t_props.tp_abitrate < 16) {
octx->flags |= CODEC_FLAG_QSCALE;
octx->global_quality = t->t_props.tp_abitrate * FF_QP2LAMBDA;
octx->bit_rate = 0;
}
break;

default:
Expand Down Expand Up @@ -1468,8 +1519,8 @@ transcoder_init_audio(transcoder_t *t, streaming_start_component_t *ssc)

if(tp->tp_channels > 0)
as->aud_channels = tp->tp_channels;

as->aud_bitrate = as->aud_channels * 64000;
if(tp->tp_abitrate > 0)
as->aud_bitrate = tp->tp_abitrate * 1000;

as->resample_context = NULL;
as->fifo = NULL;
Expand Down

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