From 6cbbf0592f4f3940aac7f687850d1b726a2ea836 Mon Sep 17 00:00:00 2001 From: "Timothy B. Terriberry" Date: Mon, 13 Oct 2014 17:46:00 -0700 Subject: resample: Avoid off-by-1 errors in PTS calcs. 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 --- libavfilter/af_resample.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'libavfilter') diff --git a/libavfilter/af_resample.c b/libavfilter/af_resample.c index bc8fd8a731..a59e6f8fd1 100644 --- a/libavfilter/af_resample.c +++ b/libavfilter/af_resample.c @@ -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; -- cgit v1.2.3