ffmpeg:encoding:gpu_encoding
Table of Contents
ffmpeg - Encoding - GPU Encoding
Convert videos to H.265 / HEVC using ffmpeg and GPU hardware encoding
ffmpeg -i "input.mkv" -vaapi_device /dev/dri/renderD128 -vf 'format=nv12,hwupload,scale_vaapi=w=1920:h=1080' -map 0:v -metadata:s:v:0 language=eng -map 0:a -metadata:s:a:0 language=eng -map 0:s? -metadata:s:s:0 language=eng -profile:v main -c:v hevc_vaapi -c:a copy -c:s copy -rc_mode CQP -global_quality 25 -v verbose "output.mkv" ffmpeg -i "input.mkv" -vaapi_device /dev/dri/renderD128 -vf 'format=nv12,hwupload,scale_vaapi=w=1920:h=1080' -map 0:v -metadata:s:v:0 language=eng -map 0:a:m:language:eng? -metadata:s:a:0 language=eng -map 0:s? -metadata:s:s:0 language=eng -profile:v main -c:v hevc_vaapi -c:a copy -c:s copy -rc_mode CQP -global_quality 25 -v verbose "output.mkv"
Explanation
ffmpeg -i "input.mkv" \ -vaapi_device /dev/dri/renderD128 \ -vf 'format=nv12,hwupload,scale_vaapi=w=1920:h=1080' \ -map 0:v -metadata:s:v:0 language=eng \ -map 0:a -metadata:s:a:0 language=eng \ -map 0:s? -metadata:s:s:0 language=eng \ -c:v hevc_vaapi \ -c:a copy \ -c:s copy \ -rc_mode CQP \ -global_quality 25 \ -profile:v main \ -v verbose \ "output.mkv"
NOTE:
- -i “input.mkv” is the source file.
- -vaapi_device /dev/dri/renderD128 is a shortcut to -init_hw_device vaapi=vaapi0:/dev/dri/renderD128 -filter_hw_device vaapi0, and initializes a new hardware device of type vaapi.
- -vf 'format=nv12,hwupload,scale_vaapi=w=1920:h=1080' creates the filtergraph and use it to filter the stream.
- The encoders only accept input as VAAPI surfaces. If the input is in normal memory, it will need to be uploaded before giving the frames to the encoder - in the ffmpeg utility, the hwupload filter can be used for this.
- It will upload to a surface with the same layout as the software frame, so it may be necessary to add a format filter immediately before to get the input into the right format (hardware generally wants the nv12 layout).
- The hwupload filter also requires a device to upload to, which needs to be defined before the filter graph is created which is done with -vaapi_device.
- The scale_vaapi=w=1920:h=1080 scales the video to 1080p.
- Use -vf 'format=nv12,hwupload' to not do any scaling.
- -map 0:v selects the Video streams from the inputs which will go into the output.
- -metadata:s:v:0 language=eng has the output Video stream to show English as the language.
- -map 0:a selects the Audio streams from the inputs which will go into the output.
- -map 0:s? selects the Sub-Title streams from the inputs which will go into the output.
- The “?” is to have this optional, i.e. only write Sub-Titles if they exist in the source.
- -c:v hevc_vaapi converts the input file to H.265 in the destination file.
- hevc_vaapi means H.265 / MPEG-H part 2 (HEVC).
Instead of using the H.265 codec, optionally select any other code that the GPU supports.
To figure out for which codecs the GPU supports, run the following command:
vainfo
This returns something like this:
VAProfileH264ConstrainedBaseline: VAEntrypointVLD VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice VAProfileH264Main : VAEntrypointVLD VAProfileH264Main : VAEntrypointEncSlice VAProfileH264High : VAEntrypointVLD VAProfileH264High : VAEntrypointEncSlice VAProfileHEVCMain : VAEntrypointVLD VAProfileHEVCMain : VAEntrypointEncSlice VAProfileHEVCMain10 : VAEntrypointVLD VAProfileHEVCMain10 : VAEntrypointEncSlice VAProfileJPEGBaseline : VAEntrypointVLD VAProfileVP9Profile0 : VAEntrypointVLD VAProfileVP9Profile2 : VAEntrypointVLD VAProfileAV1Profile0 : VAEntrypointVLD VAProfileAV1Profile0 : VAEntrypointEncSlice VAProfileNone : VAEntrypointVideoProc
For all entries with a value of VAEntrypointEncSlice hardware encoding is supported and can be used.
- -c:a copy copies the Audio streams without modification to the output.
- -c:s copy copies the Subtitle streams without modification to the output.
- -rc_mode CQP sets the rate control mode to CQP.
- CQP works well.
Run the following to see all possible modes:
ffmpeg -h encoder=hevc_vaapi
This returns all H.265 VAAPI options. These are the available rate control modes:
... -rc_mode <int> E..V....... Set rate control mode (from 0 to 6) (default auto) auto 0 E..V....... Choose mode automatically based on other parameters CQP 1 E..V....... Constant-quality CBR 2 E..V....... Constant-bitrate VBR 3 E..V....... Variable-bitrate ICQ 4 E..V....... Intelligent constant-quality QVBR 5 E..V....... Quality-defined variable-bitrate AVBR 6 E..V....... Average variable-bitrate ...
- -global_quality 25 selects the video quality.
- The default value is 25 which returns decent enough output.
- The lower the value, the better is the video quality, but the output file gets larger.
- -profile:v main selects the x265 profile, main, which should work with every output device.
- For h.265, main is the default profile. All decoders, which can decode h.265, will support it.
- But there are other profiles that can be used, for supporting additional decoder capabilities like higher colour depth (10, 12 or 16 bit), less subsampling (4:2:2 or 4:4:4) or intra-constrained (mainly for editing, as it's not efficient). Plus more specialized things.
- Main 10 is fine to use for 8 or 10 bit color depths and its inclusion in version 1 of the standard means it will enjoy a high level of support as long as the decoder supports 10 bit.
- -v verbose
- output.mkv is the output file.
References
ffmpeg/encoding/gpu_encoding.txt · Last modified: 2024/09/15 08:41 by peter