[FFmpeg-devel] [PATCH] avfilter/af_atempo: Make ffplay display correct timestamps when seeking

[Paul B Mahol]

On 5/8/19, Pavel Koshevoy <pkoshevoy at gmail.com> wrote:
> NOTE: this is a refinement of the patch from Paul B Mahol
> offset all output timestamps by same amount of first input timestamp
> ---
>  libavfilter/af_atempo.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c
> index bfdad7d76b..688dac5464 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;
>
> @@ -186,6 +189,7 @@ static void yae_clear(ATempoContext *atempo)
>
>      atempo->nfrag = 0;
>      atempo->state = YAE_LOAD_FRAGMENT;
> +    atempo->start_pts = AV_NOPTS_VALUE;
>
>      atempo->position[0] = 0;
>      atempo->position[1] = 0;
> @@ -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 +1101,11 @@ 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 = av_rescale_q(src_buffer->pts,
> +                                         inlink->time_base,
> +                                         outlink->time_base);
> +
>      while (src < src_end) {
>          if (!atempo->dst_buffer) {
>              atempo->dst_buffer = ff_get_audio_buffer(outlink, n_out);
> --
> 2.16.4
>
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Should be fine.