Project page: https://gitlab.com/AOMediaCodec/SVT-AV1
Patches: https://gitlab.com/AOMediaCodec/SVT-AV1/-/tree/master/ffmpeg_plugin?ref_type=heads

Extract svt-av1 git repository
$ git clone https://gitlab.com/AOMediaCodec/SVT-AV1.git

Modify patches to be in -p0 mode:
$ cd SVT-AV1/ffmpeg_plugin/n4.4/
$ sed -i -e 's?--- a/?--- ?1' \
         -e 's?+++ b/?+++ ?1' \
         *.patch

Rename the patches:
$ i=2001 && ls -1 *.patch | while read LINE; do echo $(printf "%04d" $i)-libsvtav1-$LINE; mv $LINE $(printf "%04d" $i)-libsvtav1-$LINE; let i++; done

Test the patches on a clean ffmpeg tree:
$ tar -jxvf ffmpeg-4.4.4.tar.bz2 
$ cd ffmpeg-4.4.4/
$ ls -1d ~/SVT-AV1/ffmpeg_plugin/n4.4/20*.patch | while read LINE; do patch -p0 < $LINE; done

Local addition (not from the upstream ffmpeg_plugin sets):
- 2026-libsvtav1-0026-support-svt-av1-3.x-and-4.x-API.patch
  Version guards for SVT-AV1 >= 3.0.0 (2-argument svt_av1_enc_init_handle)
  and >= 4.0.0 (aq_mode replaces enable_adaptive_quantization), modeled on
  the ffmpeg 8.1 libsvtav1 wrapper. Required to build against svt-av1 4.x.
