[FFmpeg-trac] #10476(avfilter:new): Regression: vpp_qsv and scale_qsv issues maintaining pts

[FFmpeg]

#10476: Regression: vpp_qsv and scale_qsv issues maintaining pts
-------------------------------------+-------------------------------------
             Reporter:  Steve        |                     Type:  defect
  Browne                             |
               Status:  new          |                 Priority:  normal
            Component:  avfilter     |                  Version:  6.0
             Keywords:  scale_qsv    |               Blocked By:
  vpp_qsv                            |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 After upgrading from ffmpeg 5.1.3 to ffmpeg 6.0 the pts values from our
 calls to `av_buffersink_get_frame` are always 0. We're expecting the
 output pts values to match input pts values since we don't do any
 framerate or time_base conversion.

 How to reproduce:
 {{{
 Graph Desc: scale_qsv=w=640:h=360
 Input Args: video_size=1920x1080:pix_fmt=114:time_base=1/90000
 }}}

 Simplified psuedo-code:
 {{{
 // Setup the graph
 avfilter_graph_parse2()
 av_buffersrc_parameters_set()
 avfilter_graph_create_filter()
 avfilter_link()
 avfilter_graph_config()

 // Input frames
 av_buffersrc_add_frame_flags()

 // Recieve output frames
 av_buffersink_get_frame()
 }}}

 Workaround:
 I was able to workaround this, but it's a bit gross in my opinion.
 Basically you need the outlink time_base in vf_vpp_qsv.c to match your
 input time_base, but there's no way to set that. It's hard-coded to always
 be the inverse of the vpp framerate. So instead you have to set the
 framerate in your graph description to the inverse of your input
 time_base. Ours happens to match the hard-coded default_tb (1/90000) in
 qsvvpp.c, but if it didn't then it may potentially have rounding errors
 converting to default_tb then back to your desired time_base.

 The conversion happens in qsvvpp.c on this line:
 {{{
 out_frame->frame->pts = av_rescale_q(out_frame->surface.Data.TimeStamp,
                                              default_tb,
 outlink->time_base);
 }}}

 The modified parameters with the framerate to workaround this are:
 {{{
 Graph Desc: vpp_qsv=w=640:h=360:framerate=90000
 Input Args:
 video_size=1920x1080:pix_fmt=114:time_base=1/90000:frame_rate=90000
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10476>
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