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Peter, I looked on Reddit for some help on my hardware roadmap and someone with a lot more knowledge on video encoding mentioned that libvpx has been updated to support 8 threads instead of just 4 when encoding to VP9. Is this something that can be updated by getting a newer version of FFMPEG?
Link to thread:
https://www.reddit.com/r/Amd/comment...nking_3600_or/
Yes getting a newer version of ffmpeg could help but this may also break transcoding in Mezzmo if the commandline parameters to ffmpeg have changed. You can get a newer ffmpeg version from https://ffmpeg.zeranoe.com/builds/ and then change the path in Transcoding settings to the path to the new ffmpeg to see if it works.
I've completed a couple of my AMD hardware upgrades to Ryzen 3000 CPUs. Here's some comparisons using FFMPEG doing 24 mbps H264 encoding.
27 fps - AMD FX-8350 1080P H.264
48 fps - Intel i7-4790k 1080P H.264
123 fps - Ryzen 3800X 1080P H.264
354 fps - Intel i7-4790K 1080P H.264 w/Nvidia 970 GPU
I've done one more upgrade, my video card from a GTX 970 to a GTX 2070 Super card. Here's the updated results:
27 fps - AMD FX-8350 1080P H.264
48 fps - Intel i7-4790k 1080P H.264
123 fps - Ryzen 3800X 1080P H.264
354 fps - Intel i7-4790K 1080P H.264 w/Nvidia 970 GPU
535 fps - Intel i7-4790K 1080P H.264 w/Nvidia 2070 Super GPU
The bottleneck becomes how fast the GPU can decode the source file. The decode process is running the GPU at 100%. The source is a Blu-Ray ISO. If I move down to DVDs I can get fps rates over 1300fps.
I've completed a hardware upgrade of my main Mezzmo server to a Ryzen 3700X CPU and completed some additional software only transcoding testing using the new hardware. The results can be found at:
Transcoding test results
I've decided that the software only results are good enough that I am not putting an nVidia card back in the server. One odd thing I noticed was that the VP8 results had low CPU utilization due to ffmpeg only leveraging one core on the CPU. I checked the FFmpegAdditional.xml file and the VP8 line is:
<ffmpegadditional id="vpx+encoding">-threads 4 -cpu-used 4 -crf 22 -qmin 10 -qmax 42</ffmpegadditional>
which I think should leverage 4 threads instead of 1. I'll need to research this further and if I can get ffmpeg to leverage more threads for VP8 I will republish the results.
Yep, you are getting the same thing with VP8 that I am getting. I am not an encoding genius but I would be really interested in any way to get the thread count up.Quote:
Originally Posted by jbinkley60
I'll let Peter or Paul weigh in here. I had worked with Peter before on this and adjusting the threads and CPU parameters in the vpx encoding line worked previously on my FX-8350 CPU. If you want to try it yourself find the FFmpegAdditional.xml file located in your device profiles directory.
The default line is: <ffmpegadditional id="vpx+encoding">-threads 4 -cpu-used 4 -crf 22 -qmin 10 -qmax 42</ffmpegadditional>
I had changed mine to: <ffmpegadditional id="vpx+encoding">-threads 4 -cpu-used 8 -crf 22 -qmin 10 -qmax 42</ffmpegadditional>
and was seeing higher CPU utilization and VP8 encoding rates. It doesn't seem to be working with my new Ryzen CPU. One interesting thing is that the ASUS motherboards I am using have CPU virtualization disabled by default. I don't think ffmpeg leverages CPU virtualization. This may have something to do with the version of ffmpeg in Mezzmo vs. how new the Ryzen Zen 2 based CPUs are. For me I can watch the videos fine (i.e. transcoding fps rate is high enough) but I would like to see better CPU utilization, like I did with my FX-8350.
Update:
I enabled CPU virtualization for my Ryzen 3700X and no difference in VP8 encoding using more threads. I didn't expect it would but wanted to rule that out.
Dissappointing, since my new system is based on a Ryzen 3500x. I'm still gonna try it, though. Thanks for the tips.Quote:
Originally Posted by jbinkley60
Looks like encoding is limited by libvpx based upon the resolution (from https://stackoverflow.com/questions/...to-4-threads):
It appears that 16 threads is the maximum and this uses 4 cores https://askubuntu.com/questions/6912...ith-vp9-ffmpegQuote:
Libvpx uses tile threading, which means you can at most have as many threads as the number of tiles. The -tile-columns option is in log2 format (so -tile-columns 6 means 64 tiles), but is also limited by the framesize. The exact details are here, it basically means that max_tiles = max(1, exp2(floor(log2(sb_cols)) - 2)), where sb_cols = ceil(width / 64.0). You can write a small script to calculate the number of tiles for a given horizontal resolution:
Width: 320 (sb_cols: 5), min tiles: 1, max tiles: 1
Width: 640 (sb_cols: 10), min tiles: 1, max tiles: 2
Width: 1280 (sb_cols: 20), min tiles: 1, max tiles: 4
Width: 1920 (sb_cols: 30), min tiles: 1, max tiles: 4
Width: 3840 (sb_cols: 60), min tiles: 1, max tiles: 8
So even for 1080p (1920 horizontal pixels), you only get 4 tiles max, so 4 threads max, i.e. a bitstream limitation. To get 8 tiles, you need at least a width of 1985 pixels (2048-64+1, which gives sb_cols=32). To get more threads than the max. number of tiles at a given resolution, you need frame-level multithreading, which libvpx doesn't implement. Other encoders, like x265/x264, do implement this.
[edit] as some people in comments and below have already commented, more recent versions of libvpx support -row-mt 1 to enable tile row multi-threading. This can increase the number of tiles by up to 4x in VP9 (since the max number of tile rows is 4, regardless of video height). To enable this, use -tile-rows N where N is the number of tile rows in log2 units (so -tile-rows 1 means 2 tile rows and -tile-rows 2 means 4 tile rows). The total number of active threads will then be equal to $tile_rows * $tile_columns.
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Originally Posted by smitbret
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