ffmpeg h.265 -crf problems :(

[niftybunny]

Hello,

I want to convert a lot of movies from h.264 to the new h.265 codex. To do this I bought a new shiny GTX 960. Installation guide here:

http://www.cnx-software.com/2016/01/04/faster-h-265hevc-video-encoding-with-nvidia-gtx...pu-and-ffmpeg/

Good news is: Its working and its really really fast.

Bad news is: -crf xx doesnt work at all

I get the warning:

Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (2Fast2Furious(1080p HD).m4v) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.

FFmpeg simply ignores the -crf option and converts every movie with 2000kbit even if its a shitty 320x200 movie. -b:v 2000k works perfectly well but I cant check the resolution of a few 100 movies to change the -b:v every time.

Is there a good workaround to make -crf work again?

My config:

ffmpeg version N-78958-g8c24523 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.1)
configuration: --prefix=/home/bunny/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/bunny/ffmpeg_build/include --extra-ldflags=-L/home/bunny/ffmpeg_build/lib --bindir=/home/bunny/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-nvenc --enable-libxvid --enable-nonfree
libavutil 55. 19.100 / 55. 19.100
libavcodec 57. 28.100 / 57. 28.100
libavformat 57. 28.100 / 57. 28.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 39.102 / 6. 39.102
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100

Thank you for reading,

Niftybunny

[TorBru]

Try "-x265-params crf=xx" instead of the generic "-crf xx".

[Baldrick]

Does it work if you don't use the GPU nvenc_hevc? Maybe is CRF not supported with the GPU encoder.

[niftybunny]

Try "-x265-params crf=xx" instead of the generic "-crf xx".

ffmpeg version N-78958-g8c24523 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.1)
configuration: --prefix=/home/bunny/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/bunny/ffmpeg_build/include --extra-ldflags=-L/home/bunny/ffmpeg_build/lib --bindir=/home/bunny/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-nvenc --enable-libxvid --enable-nonfree
libavutil 55. 19.100 / 55. 19.100
libavcodec 57. 28.100 / 57. 28.100
libavformat 57. 28.100 / 57. 28.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 39.102 / 6. 39.102
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Unrecognized option 'x265-params crf=20'.

Gives me an error msg

[niftybunny]

Does it work if you don't use the GPU nvenc_hevc? Maybe is CRF not supported with the GPU encoder.

Yes, it works. I also think that its not enabled by the GPU nvenc. That rises the question how to enable it. Or is it a feature that only a few selected codex support?

[poisondeathray]

CRF is not supported by NVEnc SDK for GPU encoding, and you probably didn't compile ffmpeg with x265 (the CPU encoder, --enable-libx265)

To see which switches are enabled in your FFMpeg NVEnc version, look under -h full, under the NVEnc section .

Also, NVEnc HEVC doesn't use b-frames (lower compression , lower quality at a given bitrate)

[niftybunny]

CRF is not supported by NVEnc SDK for GPU encoding, and you probably didn't compile ffmpeg with x265 (the CPU encoder, --enable-libx265)

To see which switches are enabled in your FFMpeg NVEnc version, look under -h full, under the NVEnc section .

Also, NVEnc HEVC doesn't use b-frames (lower compression , lower quality at a given bitrate)

Okay, I am out of luck ((

Thank you for the answer.

[LigH.de]

Indeed, the CRF quantization control is rather exclusive to the software-only encoders x264 and x265. I don't know any other encoders offering a similar feature. But well, I don't know all of them...