[FFmpeg-devel] [PATCH] avfilter/af_atempo: offset all output timestamps by same amount of first input timestamp
Pavel Koshevoy
pkoshevoy at gmail.com
Wed May 8 06:02:34 EEST 2019
On 5/7/19 8:41 PM, Pavel Koshevoy wrote:
> On 5/6/19 6:41 AM, Paul B Mahol wrote:
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>> Makes ffplay display correct timestamps when seeking.
>> ---
>> libavfilter/af_atempo.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c
>> index bfdad7d76b..6a23d59641 100644
>> --- a/libavfilter/af_atempo.c
>> +++ b/libavfilter/af_atempo.c
>> @@ -103,6 +103,9 @@ typedef struct ATempoContext {
>> // 1: output sample position
>> int64_t position[2];
>> + // first input timestamp, all other timestamps are offset by this one
>> + int64_t start_pts;
>> +
>> // sample format:
>> enum AVSampleFormat format;
>> @@ -1055,6 +1058,7 @@ static int config_props(AVFilterLink *inlink)
>> enum AVSampleFormat format = inlink->format;
>> int sample_rate = (int)inlink->sample_rate;
>> + atempo->start_pts = AV_NOPTS_VALUE;
>> return yae_reset(atempo, format, sample_rate, inlink->channels);
>> }
>> @@ -1068,7 +1072,7 @@ static int push_samples(ATempoContext *atempo,
>> atempo->dst_buffer->nb_samples = n_out;
>> // adjust the PTS:
>> - atempo->dst_buffer->pts =
>> + atempo->dst_buffer->pts = atempo->start_pts +
>> av_rescale_q(atempo->nsamples_out,
>> (AVRational){ 1, outlink->sample_rate },
>> outlink->time_base);
>> @@ -1097,6 +1101,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
>> *src_buffer)
>> const uint8_t *src = src_buffer->data[0];
>> const uint8_t *src_end = src + n_in * atempo->stride;
>> + if (atempo->start_pts == AV_NOPTS_VALUE)
>> + atempo->start_pts = src_buffer->pts;
>> while (src < src_end) {
>> if (!atempo->dst_buffer) {
>> atempo->dst_buffer = ff_get_audio_buffer(outlink, n_out);
>
>
>
> I was able to confirm from the debugger that af_atempo.c:config_props gets
> called and atempo->start_pts is reset when seeking in ffplay, so the patch
> looks okay to me.
>
> Thank you,
> Pavel.
>
However, it might be cleaner to move `atempo->start_pts = AV_NOPTS_VALUE;` from
config_props to yae_clear
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