"Lossless" Video Encoding in AVISynth?

[U2Joshua]

Searching online it appears that there is such a thing as lossless encoding using Lagarinth, however I don't see anything indicating it can be used with AVIsynth. If there is no such thing as "lossless" with AVISynth, by setting an Encode setting for CRF 0, is that (effectively) the same thing as lossless?

Thanks in advance~

[jagabo]

AviSynth doesn't encode anything. It delivers uncompressed frames to an editor/encoder. You choose the codec to use in whatever editor/encoder you use. For example, you could open an AviSynth script in VirtualDub, select the Lagarith codec, then save the video.

[sneaker]

^this. And yes, Lagarith or x264 --crf 0 (for 8 bit x264) will result in lossless encoding of these uncompressed frames. But lossless encoding will produce huge file sizes, much larger than e.g. a BluRay for the same duration/fps/resolution. That's why most people don't use it.

What many people want is to cut a compressed video losslessly while keeping the original lossy compression. This is not possible using AviSynth but tools like SolveigMM Video Splitter can do it. See: https://forum.videohelp.com/threads/375841-Editing-without-Recoding
But then you cannot do all the filtering AviSynth can do like resize, sharpen, deinterlace, deband, derainbow, deblock ...

[U2Joshua]

AviSynth doesn't encode anything. It delivers uncompressed frames to an editor/encoder. You choose the codec to use in whatever editor/encoder you use. For example, you could open an AviSynth script in VirtualDub, select the Lagarith codec, then save the video.

Ahh..., yes. Okay.

My mistake. I should have indicated that I'm used to using AVISynth with MeGui...

Is it possible to use Lagarinth with MeGui? As well..., the CRF 0 setting I mentioned was in MeGui, of course.

[jagabo]

I haven't looked at MeGUI in a long time but I'm pretty sure you can't use Lagarith with it. And you wouldn't want to unless you are generating an intermediate file for later editing/processing. Reencoding MPG files to Lagarith will make them grow in size by 10 fold.

Encoding with x264 at CRF 0 will give you lossless encoding but file sizes will also be 10x larger than your MPEG source.

Ie, lossless encoders start with uncompressed video. But your source is MPEG 2 encoded. Those MPEG 2 frames have to be decompressed, making them grow ~20 fold in size before giving them to the lossless codec. The lossless codec will shrink those uncompressed frames to about half their size. In the end, your lossless encodings will be 10x the size of your MPEG file.

[U2Joshua]

I haven't looked at MeGUI in a long time but I'm pretty sure you can't use Lagarith with it. And you wouldn't want to unless you are generating an intermediate file for later editing/processing. Reencoding MPG files to Lagarith will make them grow in size by 10 fold.

Encoding with x264 at CRF 0 will give you lossless encoding but file sizes will also be 10x larger than your MPEG source.

Ie, lossless encoders start with uncompressed video. But your source is MPEG 2 encoded. Those MPEG 2 frames have to be decompressing, making them grow ~20 fold in size before giving them to the lossless codec. The lossless codec will shrink those uncompressed frames to about half their size. In the end, your lossless encodings will be 10x the size of your MPEG file.

Got it!

Thank you.