====== ffmpeg - Encoding - GPU Encoding ======

===== Convert videos to H.265 / HEVC using ffmpeg and GPU hardware encoding =====

<code bash>
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"
</code>

----

===== Explanation =====

<code bash>
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"
</code>


<WRAP info>
**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 uses 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, and to use NV12 (8-bit encoding).
    * Use **-vf 'format=p010,hwupload'** for 10-bit encoding; and also change the profile to **Main10**.
      * See further below for other pixel formats..
  * **-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).
    * <WRAP>
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: <code bash>vainfo</code>

This returns something like this: <code>
      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
</code>

For all entries with a value of **VAEntrypointEncSlice** hardware encoding is supported and can be used.

</WRAP>

  * **-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.
    * <WRAP>
Run the following to see all possible modes: <code bash>ffmpeg -h encoder=hevc_vaapi</code>

This returns all H.265 VAAPI options. These are the available rate control modes:

<code bash>
...
  -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
...
</code>

</WRAP>

  * **-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.

</WRAP>


----

===== Using other pixel formats =====

Check which pixel formats are supported:

<code bash>
ffmpeg -pix_fmts
</code>

returns

<code>
Pixel formats:
I.... = Supported Input  format for conversion
.O... = Supported Output format for conversion
..H.. = Hardware accelerated format
...P. = Paletted format
....B = Bitstream format
FLAGS NAME            NB_COMPONENTS BITS_PER_PIXEL BIT_DEPTHS
-----
IO... yuv420p                3             12      8-8-8
IO... yuyv422                3             16      8-8-8
...
...
IO... nv12                   3             12      8-8-8
IO... p010le                 3             15      10-10-10
</code>

----

<WRAP info>
**NOTE:** When using a different pixel format, usually the following options will need to be set:

  * -vf 'format=nv12' and -profile:v main
  * -vf 'format=p010' and -profile:v main10
  * -vf 'format=p016' and -profile:v rext

</WRAP>

----

==== Encode with 8-bit ====

^Format^Chroma sampling^Packed or planar^Bits per channel^
|NV12|4:2:0|Planar|8|

<code bash>
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"
</code>

==== Encode with 10-bit ====

^Format^Chroma sampling^Packed or planar^Bits per channel^
|P010|4:2:0|Planar|10|

<code bash>
ffmpeg -i "input.mkv" -vaapi_device /dev/dri/renderD128 -vf 'format=p010,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 main10 -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=p010,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 main10 -c:v hevc_vaapi -c:a copy -c:s copy -rc_mode CQP -global_quality 25 -v verbose "output.mkv"
</code>

==== Encode with 16-bit ====

^Format^Chroma sampling^Packed or planar^Bits per channel^
|P010|4:2:0|Planar|16|

<code bash>
ffmpeg -i "input.mkv" -vaapi_device /dev/dri/renderD128 -vf 'format=p016,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 rext -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=p016,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 rext -c:v hevc_vaapi -c:a copy -c:s copy -rc_mode CQP -global_quality 25 -v verbose "output.mkv"
</code>


----

===== References =====

https://trac.ffmpeg.org/wiki/Hardware/VAAPI

https://trac.ffmpeg.org/wiki/Encode/H.265

https://ffmpeg.org/ffmpeg-filters.html