FF Transcode Advanced options

The “Advanced” tab allows users (who know what they are doing) to pass extra FFmpeg options to the transcoding task. Use “at your own risk”. We are not providing complete support for the possibilities permitted as they are endless. But note that in some cases extra options can conflict with default values, so a transcoding job may fail due to the extra options you may add.

One commonly asked feature is a quality setting for h.264 and h.265 outputs. The h.264 and h.265 presets are meant, by default, to generate small, highly compressed files. FF Transcode is not meant to be a full feature video encoder, so fine tuning all the codecs settings is not on the agenda, but a basic control of the output file quality is possible thanks to the advanced options.

This can be done by specifying a quality factor (“CRF” – Constant Rate Factor) and an encoding speed in the “Extra output options”. Note that this will be better and more efficient (for these codecs, at least) than explicitly setting a given constant bitrate, as the quality you get for a given bitrate will depend on the encoder, and most of all of what you encode!
To set the quality for h.264 or h.265 exports in FF Transcode, write the following (excluding quotes) in the “Extra output options” of the “Advanced” tab:
“-crf 20 -preset slow”
Encoding slower will increase your quality, while not changing the size/bitrate. If you don’t want this, you can just remove “-preset slow”.
CRF is a number describing a “quality” factor. By default it is 28 for h.265 and 23 for h.264. SMALLER values mean higher quality!
Be careful that it is exponential so that decreasing the number a bit will quickly result in substantially heavier files. We recommend testing to find the right number for your needs.

If for some reason you prefer a constant bitrate, you can instead pass the following option: “-b:v 2M”, where “2M” is 2 megabytes. Change the value according to your needs (using ‘M’ for megabyte and ‘k’ for kilobyte).

Finally, you can also set a variable bitrate more explicitly than using the CRF quality factor by passing the following: “-b:v 1M -minrate 500k -maxrate 2M -bufsize 2M”, setting the desired average value (1M), a minimum and a maximum. Set the buffer size to the maximum rate value.