[FFmpeg-devel] [PATCH] fftools/ffmpeg.c: allow forcing input framerate on streamcopy

[Leo Izen]

On 10/19/18 3:02 PM, Carl Eugen Hoyos wrote:
> 2018-10-19 20:39 GMT+02:00, Leo Izen <leo.izen at gmail.com>:
>> On 10/19/18 2:26 PM, Carl Eugen Hoyos wrote:
>>> 2018-10-19 4:58 GMT+02:00, Leo Izen <leo.izen at gmail.com>:
>>>> ---
>>>>    fftools/ffmpeg.c | 8 +++++---
>>>>    1 file changed, 5 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
>>>> index da4259a9a8..5d68194676 100644
>>>> --- a/fftools/ffmpeg.c
>>>> +++ b/fftools/ffmpeg.c
>>>> @@ -2045,12 +2045,14 @@ static void do_streamcopy(InputStream *ist,
>>>> OutputStream *ost, const AVPacket *p
>>>>        if (ost->enc_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
>>>>            ost->sync_opts++;
>>>>
>>>> -    if (pkt->pts != AV_NOPTS_VALUE)
>>>> +    if (ist->framerate.num)
>>>> +        opkt.pts = av_rescale_q(ist->pts, AV_TIME_BASE_Q,
>>>> ost->mux_timebase) - ost_tb_start_time;
>>>> +    else if (pkt->pts != AV_NOPTS_VALUE)
>>>>            opkt.pts = av_rescale_q(pkt->pts, ist->st->time_base,
>>>> ost->mux_timebase) - ost_tb_start_time;
>>>>        else
>>>>            opkt.pts = AV_NOPTS_VALUE;
>>>>
>>>> -    if (pkt->dts == AV_NOPTS_VALUE)
>>>> +    if (pkt->dts == AV_NOPTS_VALUE || ist->framerate.num)
>>>>            opkt.dts = av_rescale_q(ist->dts, AV_TIME_BASE_Q,
>>>> ost->mux_timebase);
>>>>        else
>>>>            opkt.dts = av_rescale_q(pkt->dts, ist->st->time_base,
>>>> ost->mux_timebase);
>>>> @@ -2602,7 +2604,7 @@ static int process_input_packet(InputStream *ist,
>>>> const AVPacket *pkt, int no_eo
>>>>            avpkt = *pkt;
>>>>        }
>>>>
>>>> -    if (pkt && pkt->dts != AV_NOPTS_VALUE) {
>>>> +    if (pkt && pkt->dts != AV_NOPTS_VALUE && !ist->framerate.num) {
>>>>            ist->next_dts = ist->dts = av_rescale_q(pkt->dts,
>>>> ist->st->time_base, AV_TIME_BASE_Q);
>>>>            if (ist->dec_ctx->codec_type != AVMEDIA_TYPE_VIDEO ||
>>>> !ist->decoding_needed)
>>>>                ist->next_pts = ist->pts = ist->dts;
>>> How can this be tested?
>>>
>>> Carl Eugen
>> I'm not entirely sure. I ran "make fate" and it passed, and I
>> successfully rescaled a 30fps clip to 15fps, 20fps, 45fps, and 60fps
>> using -r:v as an input option. I'm not entirely sure what the standard
>> procedure is for performing more rigorous tests.
> What I meant was:
> Which kind of input and output did you use to test your patch?
>
> Carl Eugen
> _______________________________________________

It worked perfectly at various framerates for AVI files. It also worked 
in practice for MP4 and Matroska files, although my patch doesn't 
properly set the avg_frame_rate and r_frame_rate of the output stream. 
Intelligent players like MPV play it fine and ignore the incorrect 
*_frame_rate metadata. Anyway, here's an updated patch that fixes that 
problem so it shouldn't be an issue.

Leo Izen

---
  fftools/ffmpeg.c | 19 ++++++++++++++-----
  1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index da4259a9a8..6e81716795 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -2045,12 +2045,14 @@ static void do_streamcopy(InputStream *ist, 
OutputStream *ost, const AVPacket *p
      if (ost->enc_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
          ost->sync_opts++;

-    if (pkt->pts != AV_NOPTS_VALUE)
+    if (ist->framerate.num)
+        opkt.pts = av_rescale_q(ist->pts, AV_TIME_BASE_Q, 
ost->mux_timebase) - ost_tb_start_time;
+    else if (pkt->pts != AV_NOPTS_VALUE)
          opkt.pts = av_rescale_q(pkt->pts, ist->st->time_base, 
ost->mux_timebase) - ost_tb_start_time;
      else
          opkt.pts = AV_NOPTS_VALUE;

-    if (pkt->dts == AV_NOPTS_VALUE)
+    if (pkt->dts == AV_NOPTS_VALUE || ist->framerate.num)
          opkt.dts = av_rescale_q(ist->dts, AV_TIME_BASE_Q, 
ost->mux_timebase);
      else
          opkt.dts = av_rescale_q(pkt->dts, ist->st->time_base, 
ost->mux_timebase);
@@ -2602,7 +2604,7 @@ static int process_input_packet(InputStream *ist, 
const AVPacket *pkt, int no_eo
          avpkt = *pkt;
      }

-    if (pkt && pkt->dts != AV_NOPTS_VALUE) {
+    if (pkt && pkt->dts != AV_NOPTS_VALUE && !ist->framerate.num) {
          ist->next_dts = ist->dts = av_rescale_q(pkt->dts, 
ist->st->time_base, AV_TIME_BASE_Q);
          if (ist->dec_ctx->codec_type != AVMEDIA_TYPE_VIDEO || 
!ist->decoding_needed)
              ist->next_pts = ist->pts = ist->dts;
@@ -3158,8 +3160,15 @@ static int 
init_output_stream_streamcopy(OutputStream *ost)
          else
              sar = par_src->sample_aspect_ratio;
          ost->st->sample_aspect_ratio = par_dst->sample_aspect_ratio = sar;
-        ost->st->avg_frame_rate = ist->st->avg_frame_rate;
-        ost->st->r_frame_rate = ist->st->r_frame_rate;
+
+        if (ist->framerate.num) {
+            ost->st->avg_frame_rate = ist->framerate;
+            ost->st->r_frame_rate = ist->framerate;
+        } else {
+            ost->st->avg_frame_rate = ist->st->avg_frame_rate;
+            ost->st->r_frame_rate = ist->st->r_frame_rate;
+        }
+
          break;
      }

-- 
2.19.1