[FFmpeg-trac] #9884(undetermined:new): CRF affects the number of produced frames in VP9

[FFmpeg]

#9884: CRF affects the number of produced frames in VP9
-------------------------------------+-------------------------------------
             Reporter:  Athari       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I have 12 input frames in PNG format. When I encode WebM+VP9 with `-crf
 0`, I get a video with 3 frames. When I encode with `-crf 20`, I get 6
 frames. When I encode with `-crf 40`, I get 12 frames. MKVToolNix info
 tool confirms that there're only 3/6 block groups in the clusters of the
 incomplete videos.

 FFMPEG reads all 12 frames, encodes all 12 frames, but then muxes only 3
 packets with no explanation.

 Changing the container (MKV, MP4, IVF) doesn't affect the result. Encoding
 with VP8 always produces a video with the correct duration (ranging from
 `-c:v libvpx -crf 63 -qmin 63 -qmax 63 -b:v 500 -auto-alt-ref 0` to `-c:v
 libvpx -crf 0 -qmin 0 -qmax 0 -b:v 100M -auto-alt-ref 0`). I tried
 changing various parameters of VP9 too, but none of them affected the
 result. Other sequences of frames seem to be encoded correctly with the
 same arguments.

 Output from `-crf 0`:
 {{{
 > ffmpeg -y -loglevel debug -r 10 -i "%04d.png" -framerate 10 -crf 0
 "_.webm"
 ffmpeg version 2022-05-08-git-f77ac5131c-full_build-www.gyan.dev Copyright
 (c) 2000-2022 the FFmpeg developers
   built with gcc 11.3.0 (Rev1, Built by MSYS2 project)
   configuration: --enable-gpl --enable-version3 --enable-static --disable-
 w32threads --disable-autodetect --enable-fontconfig --enable-iconv
 --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma
 --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt
 --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray
 --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libdavs2
 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1
 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2
 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg
 --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r
 --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-
 libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-
 llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc
 --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc
 --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio
 --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-
 libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora
 --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-
 libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex
 --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite
 --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-
 chromaprint
   libavutil      57. 24.101 / 57. 24.101
   libavcodec     59. 27.100 / 59. 27.100
   libavformat    59. 23.100 / 59. 23.100
   libavdevice    59.  6.100 / 59.  6.100
   libavfilter     8. 38.100 /  8. 38.100
   libswscale      6.  6.100 /  6.  6.100
   libswresample   4.  6.100 /  4.  6.100
   libpostproc    56.  5.100 / 56.  5.100
 ...

 Output #0, webm, to '_.webm':
   Metadata:
     encoder         : Lavf59.23.100
   Stream #0:0, 0, 1/1000: Video: vp9, 1 reference frame, yuva420p(tv,
 progressive), 100x100 (0x0) [SAR 1:1 DAR 1:1], 0/1, q=2-31, 10 fps, 1k tbn
     Metadata:
       encoder         : Lavc59.27.100 libvpx-vp9
     Side data:
       cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
 Clipping frame in rate conversion by 0.000008
 cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless
 if it occurs once at the start per stream)
     Last message repeated 12 times
 [out_0_0 @ 000001a5138c5ec0] EOF on sink link out_0_0:default.
 ...

 [webm @ 000001a5137ef8c0] Writing block of size 7331 with pts 200, dts
 200, duration 100 at relative offset 17446 in cluster at offset 494.
 TrackNumber 1, keyframe 0
 [webm @ 000001a5137ef8c0] end duration = 300
 [webm @ 000001a5137ef8c0] stream 0 end duration = 300
 frame=   12 fps=0.0 q=0.0 Lsize=      26kB time=00:00:00.20
 bitrate=1048.1kbits/s speed=0.487x
 video:22kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 17.963535%
 Input file #0 (%04d.png):
   Input stream #0:0 (video): 12 packets read (202119 bytes); 12 frames
 decoded;
   Total: 12 packets (202119 bytes) demuxed
 Output file #0 (_.webm):
   Output stream #0:0 (video): 12 frames encoded; 3 packets muxed (22323
 bytes);
   Total: 3 packets (22323 bytes) muxed
 [AVIOContext @ 000001a51385f5c0] Statistics: 26333 bytes written, 0 seeks,
 1 writeouts
 12 frames successfully decoded, 0 decoding errors
 }}}

 The attached archive includes input frames, output videos, full logs in
 debug mode produced with 3 different CRF values.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9884>
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