[FFmpeg-devel] [PATCH] libavfilter/af_atempo: offset output frames' pts by first_frame_pts / tempo

[Paweł Wegner]

Signed-off-by: Paweł Wegner <pawel.wegner95 at gmail.com>
---
 libavfilter/af_atempo.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c
index bfdad7d76b..1245eae8c1 100644
--- a/libavfilter/af_atempo.c
+++ b/libavfilter/af_atempo.c
@@ -147,6 +147,8 @@ typedef struct ATempoContext {
     uint8_t *dst_end;
     uint64_t nsamples_in;
     uint64_t nsamples_out;
+
+    int64_t first_frame_pts;
 } ATempoContext;
 
 #define YAE_ATEMPO_MIN 0.5
@@ -994,6 +996,7 @@ static av_cold int init(AVFilterContext *ctx)
     ATempoContext *atempo = ctx->priv;
     atempo->format = AV_SAMPLE_FMT_NONE;
     atempo->state  = YAE_LOAD_FRAGMENT;
+    atempo->first_frame_pts = AV_NOPTS_VALUE;
     return 0;
 }
 
@@ -1069,6 +1072,7 @@ static int push_samples(ATempoContext *atempo,
 
     // adjust the PTS:
     atempo->dst_buffer->pts =
+        (atempo->first_frame_pts == AV_NOPTS_VALUE ? 0 : atempo->first_frame_pts / atempo->tempo) +
         av_rescale_q(atempo->nsamples_out,
                      (AVRational){ 1, outlink->sample_rate },
                      outlink->time_base);
@@ -1108,6 +1112,11 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *src_buffer)
 
             atempo->dst = atempo->dst_buffer->data[0];
             atempo->dst_end = atempo->dst + n_out * atempo->stride;
+
+            if (atempo->first_frame_pts == AV_NOPTS_VALUE)
+                atempo->first_frame_pts = av_rescale_q(atempo->dst_buffer->pts,
+                                                       inlink->time_base,
+                                                       outlink->time_base);
         }
 
         yae_apply(atempo, &src, src_end, &atempo->dst, atempo->dst_end);
-- 
2.17.1