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jpsollie
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Joined: 17 Aug 2013
Posts: 291
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 Posted: Mon Aug 07, 2023 2:25 pm Post subject: What are my options with VCN VAAPI transcoding? |
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So, small intro:
- I got lots of ntsc mpeg2 files > 4gb which should be archived. Archived in a way it fits on a fat32 filesystem
Streaming is not a thing.
- electricity is expensive
- I use AMD for my dedicated GPU (navi23)rather thans nvidia because the non-proprietary drivers are better and it supports both vdpau and vaapi.
So, what are my options here for archiving?
- I heard the h.264 encoder on AMD sucks. That leaves only h.265 as a possibility.
- I'd like to investigate the quality loss after archiving. Simply to check. I saw ffmpeg has a PSNR filter to compare both streams, but what do those numbers say?
- is there *ANY* reason I should prefer AMF over VAAPI?
- are general options like 'compress' in ffmpeg encoder options implemented on hevc_VAAPI? Or simply ignored?
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wippie
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Joined: 27 Apr 2004
Posts: 62
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| Posted: Tue Aug 08, 2023 9:57 pm Post subject: |
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AMD hardware encoder for both h.264 and h.265 aren't awesome. They are intendent for streaming, hence they are fast rather than high quality. The same goes for nvidia tho. They can still be useful of course.
First of all, verify your VAAPI works. You can use vainfo in the media-video/libvia-utils package for this. You should see some VAEntrypointEncSlice entries in its output.
Second, you can use ffmpeg to transcode the video, using the hardware encoder. E.g for h.265 to mkv container:
| Code: | ffmpeg -i "<input video file>" -vaapi_device /dev/dri/renderD128 -vf format=nv12,hwupload -c:v hevc_vaapi -qp 25 -c:a copy -c:s copy -map 0:a? -map 0:s? -map 0:v "<output video file.mkv>"
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Adjust parameters as you see fit your needs. |
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jpsollie
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Joined: 17 Aug 2013
Posts: 291
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| Posted: Wed Aug 09, 2023 4:22 am Post subject: |
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| wippie wrote: | AMD hardware encoder for both h.264 and h.265 aren't awesome. They are intendent for streaming, hence they are fast rather than high quality. The same goes for nvidia tho. They can still be useful of course.
First of all, verify your VAAPI works. You can use vainfo in the media-video/libvia-utils package for this. You should see some VAEntrypointEncSlice entries in its output.
Second, you can use ffmpeg to transcode the video, using the hardware encoder. E.g for h.265 to mkv container:
| Code: | ffmpeg -i "<input video file>" -vaapi_device /dev/dri/renderD128 -vf format=nv12,hwupload -c:v hevc_vaapi -qp 25 -c:a copy -c:s copy -map 0:a? -map 0:s? -map 0:v "<output video file.mkv>"
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Adjust parameters as you see fit your needs. |
Yes, I knew that, thanks 
however VCN 3.0 seems to have improved its hevc encoder up to a level where I think it's pretty useful. I even decode it in hardware:
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ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -i title_t00.mkv -map 0:v -map 0:a:0 -map 0:s -c:v hevc_vaapi -rc_mode:v 1 -qp 22 -compression_level:v 7 -c:a libfdk_aac -ac:a 2 -vbr:a 3 -disposition:a:0 default -c:s copy compressed.mkv
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but honestly, I do not have a clue what those parameters mean:
- I know qp defines image quality, and I know a higher value defines a lower quality, but how high should it be set for old DVDs?
- I know compress is a ffmpeg variable that can be used in every encoder, but does vaapi actually use it?
- I know ffmpeg's PSNR filter has some ideas of calculating the difference between the reference and encoded stream, but it gives a number from 0 to 60. What numbers should be acceptable?
*EDIT*:
I based myself on this article: https://www.techpowerup.com/293494/gpu-hardware-encoders-benchmarked-on-amd-rdna2-and-nvidia-turing-architectures
so yes, amd's encoder is the worst, but as long as I'm not too constrained on bitrate (which isn't that much of a problem), the electric costs of decoding / encoding in software will probably more of a concern 
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