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Ask HN: Share your FFmpeg settings for video hosting

72 points indulona | 1 comments | 20 Jul 24 17:30 UTC | HN request time: 0.332s | source

I am working on a website that has video hosting capability. Users can upload video files and i will generate multiple versions with different qualities or just audio, thumbnails and things like that.

I have chosen the mp4 container because of how widely supported it is. To prevent users having to fetch whole files, i use the fast start option, where the container's metadata is written at the beginning of the file, instead of at the end.

Next, I have picked h264 codec because of how widely supported it is. VP8/VP9/AV1/x265/x266 are certainly better but the h264 software encoding is often beating hardware encoding due to highly optimized and time-proven code and supported hardware. And the uploaded videos are already compressed, users won't be uploading some 8k raw videos where most advanced codes would be useful for preserving "quality".

For audio, i have picked opus codec. Seems like good value over others. Not much else to add.

I run the ffmpeg to convert video with command like this:

ffmpeg -hide_banner -loglevel error -i input.mp4 -g 52 -c:v h264 -maxrate:v vbr -bufsize vbr -s HxW -c:a libopus -af aformat=channel_layouts=7.1|5.1|stereo -maxrate:a abr -ar 48000 -ac 2 -f mp4 -movflags faststart -map 0:v:0 -map 0:a:0 output.mp4

where vbr is video bitrate like 1024k(1mbps), abr is audio bitrate like 190k and HxW is video dimensions in case of resizing.

I wonder how are folks that handle video encoding process and generate their videos?

How did you pick your settings, what issues have you encountered and any tips you can share are certainly appreciated.

Quite a niche segment when it comes to operations and not being merely consumer/customer.

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adamzochowski ◴[24 Jul 24 13:30 UTC] No.41056907[source]▶
Last 3 years I traveled extensively and had limited and flakey bandwidth.

You should have a low bandwidth setting that also uses new codecs.

Like 64kbit stereo opus is to my ears almost imperceptible to CD audio. I think listening tests by professionals recommend using between 64kbit to 96kbit for perfect audio.

Anything beyond is a waste unless we are talking about more than stereo.

Also if you want, you can use mpeg dash to stream video. Here you encode video into small series of chunks/files. When player can't handle high bandwidth, it can switch to lower bandwidth automatically, and vice versa. This is what YouTube and any professional places do. This will also help prevent users from easily downloading complete video. The trick is that you will need to ensure all videos are split on same key frame, so either use two pass encoding, or define that every ?3? seconds exactly is a new video file.

https://www.cloudflare.com/en-ca/learning/video/what-is-mpeg...

replies(1): >>41057640 #
1. indulona ◴[24 Jul 24 14:46 UTC] No.41057640[source]▶
there are audio-only and 360p versions. in addition to 720p and 1080p.