Does setting the ffmpeg -preset affect quality? Does Handbrake preset?

[LaserBones]

I think I've seen a lot of misinformation. From my understanding the preset setting only affects compression not quality. My questions are, does setting the ffmpeg -preset affect quality? Likewise do different settings on the Encoder Preset in Handbrake ever affect quality?

I've read things like this for handbrake "Behind the scenes, the speed slider tells ffmpeg to either use or ignore certain types of compression opportunities that requires more CPU resources. Losing those opportunities decreases quality while having less of an impact on filesize that you'd think." Again this doesn't add up from other sources where I've read it has nothing to do with quality.

[Sharc]

One can only compare the quality on the basis of equal file sizes, not just on the selection of some 'presets' of different tools.
Presets have different meanings, they can be quality based or device based (for playback compatibility), for example.
Bottom line: A preset affects efficiency, means speed, visual quality and compression. So for the 'quality' comparison one should compare the results based on same encoded file size.

[LaserBones]

Thanks for the reply. The reasoning for asking the question above is because I'm trying to create lossless QTGMC deinterlaced files for editing. I've included what the ffmpeg manual says below. Is it saying that both are the lossless because the crf value is 0 so the preset speed doesn't matter? If I'm trying to achieve the best quality does using ultrafast as a preset matter?

You can use -crf 0 to create a lossless video. Two useful presets for this are ultrafast or veryslow since either a fast encoding speed or best compression are usually the most important factors.

Fast encoding example:
ffmpeg -i input -c:v libx264 -preset ultrafast -crf 0 output.mkv

Best compression example:
ffmpeg -i input -c:v libx264 -preset veryslow -crf 0 output.mkv

[Sharc]

Both are lossless.
The preset veryslow will require more CPU power and takes more time. The file size will be smaller. Simply speaking it's similar to a .zip which is smaller than the unzipped original, but still lossless.

[LaserBones]

Thanks so much!

[Sharc]

Just be prepared that x264 lossless (using any settings) isn't as compatible in most NLE's as some other lossless codecs. You have to try it out what your editor accepts.

[abolibibelot]

Other codecs might be more suitable as lossless intermediates.

From this post by “poisondeathray” :

Commonly used lossless compression options for windows (large filesizes, about 1/2 the size of uncompressed YV12) :
Lagarith, Huffyuv, UT video, FFV1.
Performance wise, UT video (fastest scrubbing in editors). Compression wise, FFV1 (but slow as molasses).

[jagabo]

I'm trying to create lossless QTGMC deinterlaced files for editing. I've included what the ffmpeg manual says below. Is it saying that both are the lossless because the crf value is 0 so the preset speed doesn't matter?

For crf=0 both are lossless so both are the same quality. Only the file size will differ (how much depends on the particular video). But at any other crf value the slower presets deliver better quality than the faster presets. And with the exception of ultrafast and superfast the sizes usually won't vary by more than about 10 percent (ultrafast and superfast are much larger, especially the former). And the variance isn't linear.

But why take anybody's word for it? Just try a few test encodes see for yourself.