Log Message:
multimedia/ffmpeg7: Update to 7.1

Changelog:
version 7.1:
- Raw Captions with Time (RCWT) closed caption demuxer
- LC3/LC3plus decoding/encoding using external library liblc3
- ffmpeg CLI filtergraph chaining
- LC3/LC3plus demuxer and muxer
- pad_vaapi, drawbox_vaapi filters
- vf_scale supports secondary ref input and framesync options
- vf_scale2ref deprecated
- qsv_params option added for QSV encoders
- VVC decoder compatible with DVB test content
- xHE-AAC decoder
- removed DEC Alpha DSP and support code
- VVC encoding support via libvvenc
- perlin video source
- D3D12VA HEVC encoder
- Cropping metadata parsing and writing in Matroska and MP4/MOV de/muxers
- Intel QSV-accelerated VVC decoding
- MediaCodec AAC/AMR-NB/AMR-WB/MP3 decoding
- YUV colorspace negotiation for codecs and filters, obsoleting the
  YUVJ pixel format
- Vulkan H.264 encoder
- Vulkan H.265 encoder
- stream specifiers in fftools can now match by stream disposition
- LCEVC enhancement data exporting in H.26x and MP4/ISOBMFF
- LCEVC filter
- MV-HEVC decoding