[FFmpeg-trac] #11126(ffmpeg:new): Filter "setpts=PTS-STARTPTS" in 2-pass may cause abnormal bitrate allocation

[FFmpeg]

#11126: Filter "setpts=PTS-STARTPTS" in 2-pass may cause abnormal bitrate
allocation
-------------------------------------+-------------------------------------
             Reporter:  Saul Baker   |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  ffmpeg
              Version:  git-master   |               Resolution:
             Keywords:  regression   |               Blocked By:
  setpts 2-pass                      |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Comment (by Saul Baker):

 > Would you further confirm it's irrelevant with VP9?

 Not sure, libx264 looks fine visually, and shows a much smaller difference
 that's consistent with just doing a good job at two pass, certainly not
 the same bitrate crash as vp9:

 {{{
 > ffprobe -hide_banner -threads 0 -show_entries
 "stream=time_base:format=size" -of "flat=h=0" dest_2pass_setpts.mp4
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'dest_2pass_setpts.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf61.5.101
   Duration: 00:00:41.57, start: 0.000000, bitrate: 3118 kb/s
   Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
 yuv420p(tv, bt470bg/bt470bg/smpte170m, progressive), 846x480, 3115 kb/s,
 30.02 fps, 30 tbr, 90k tbn (default)
       Metadata:
         handler_name    : VideoHandler
         vendor_id       : [0][0][0][0]
         encoder         : Lavc61.11.100 libx264
 stream.0.time_base="1/90000"
 format.size="16202087"

 > ffprobe -hide_banner -threads 0 -show_entries
 "stream=time_base:format=size" -of "flat=h=0" dest_2pass_nofilter.mp4
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'dest_2pass_nofilter.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf61.5.101
   Duration: 00:00:41.60, start: 0.000000, bitrate: 3272 kb/s
   Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
 yuv420p(tv, bt470bg/bt470bg/smpte170m, progressive), 846x480, 3269 kb/s,
 30 fps, 30 tbr, 15360 tbn (default)
       Metadata:
         handler_name    : VideoHandler
         vendor_id       : [0][0][0][0]
         encoder         : Lavc61.11.100 libx264
 stream.0.time_base="1/15360"
 format.size="17017374"
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11126#comment:20>
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