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resample: Avoid off-by-1 errors in PTS calcs.

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The rounding used in the PTS calculations in filter_frame() does
not actually match the number of samples output by the resampler.
This leads to off-by-1 errors in the timestamps indicating gaps and
underruns, even when the input timestamps are all contiguous.

Bug-Id: 753

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Timothy B. Terriberry 2014-10-13 17:46:00 -07:00 committed by Anton Khirnov
parent fb238f8230
commit 6cbbf0592f
1 changed files with 9 additions and 1 deletions
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10
libavfilter/af_resample.c
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@ -42,6 +42,7 @@ typedef struct ResampleContext {
AVDictionary *options;
int64_t next_pts;
int64_t next_in_pts;
/* set by filter_frame() to signal an output frame to request_frame() */
int got_output;
@ -154,6 +155,7 @@ static int config_output(AVFilterLink *outlink)
outlink->time_base = (AVRational){ 1, outlink->sample_rate };
s->next_pts = AV_NOPTS_VALUE;
s->next_in_pts = AV_NOPTS_VALUE;
av_get_channel_layout_string(buf1, sizeof(buf1),
-1, inlink ->channel_layout);
@ -255,7 +257,12 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
}
out->sample_rate = outlink->sample_rate;
if (in->pts != AV_NOPTS_VALUE) {
/* Only convert in->pts if there is a discontinuous jump.
This ensures that out->pts tracks the number of samples actually
output by the resampler in the absence of such a jump.
Otherwise, the rounding in av_rescale_q() and av_rescale()
causes off-by-1 errors. */
if (in->pts != AV_NOPTS_VALUE && in->pts != s->next_in_pts) {
out->pts = av_rescale_q(in->pts, inlink->time_base,
outlink->time_base) -
av_rescale(delay, outlink->sample_rate,
@ -264,6 +271,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
out->pts = s->next_pts;
s->next_pts = out->pts + out->nb_samples;
s->next_in_pts = in->pts + in->nb_samples;
ret = ff_filter_frame(outlink, out);
s->got_output = 1;