#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>
FFmpeg <https://ffmpeg.org>
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