H264 specific options¶
h264_preset¶
This sets the encoding preset for libx264. The default option is medium.
Valid options are:
| Preset | Speed relative to medium |
|---|---|
| ultrafast | 0.45 |
| superfast | ? |
| veryfast | ? |
| faster | 0.75 |
| fast | 0.9 |
| medium | 1 |
| slow | 1.4 |
| slower | 2 |
| veryslow | 2.8 |
This controls the transcoding speed/quality tradeoff. The slower options create nicer output but cost more cpu time. Usually medium is the right choise.
h264_tune¶
This sets the tune parameter for the x264 encoder. Options are:
| Tune | Usage |
|---|---|
| film | Use for high quality movie content; lowers deblocking |
| animation | Good for cartoons; uses higher deblocking and more reference frames |
| grain | Preserves the grain structure in old, grainy film material |
| stillimage | Good for slideshow-like content |
| fastdecode | Allows faster decoding by disabling certain filters |
h264_profile¶
This sets the H.264 profile that is used for encoding, it defaults to main, The valid options are:
- baseline
- main
- high
- high10
- high422
- high444
h264_crf¶
This sets the constant rate factor. The CRF controls the output quality. The default is 23, higher numbers give higher quality and lower numbers give worse quality. The range is 0-51
h264_params¶
This can be used to pass extra settings to x264
h264_faststart¶
This moves the H.264 metadata to the start of the file instead of the end, this means that browsers can start playing the files quicker but it costs slightly more time to encode. It defaults to false
h264_yuv420p¶
This forces it to translate the video to YUV420 before encoding, this is required for most video players so it is true by default.