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I've downloaded a rather vast number of videos from YouTube over the past couple of years (probably in excess of 1500) - and these are all MKV.

Unfortunately — Premiere Pro seems only capable of importing some of them, some of the time, which appears to be a whole rabbit hole in and of itself.

I would like to transcode these files into something which Premiere can import/edit without difficulty - like MP4 or WebM - and without compromising quality.

I've gone through a large number of videos on YouTube to try and find a way of doing this - but what I've found has either been extremely time-consuming or not yielded a result that's lossless.

Some have suggested various "converter" type applications - but the processing time per file (not even major files) is absolutely insane.

I've seen FFmpeg being mentioned - but is the result actually lossless?

Giacomo1968
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ReEA
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1 Answers1

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Transcoding is slow and lossy, because it literally means re-compressing the entire video frame by frame in the new format, the same way as when it was compressed in the first place. And generally, the better a codec is at compressing video without being noticeably lossy, the more processing power it'll need and the longer it'll take.

You might be able to tune the codec to do its job much faster if you can deal with the output file being 10 times larger, for example. You could even choose an 100%-lossless codec (if Premiere supports one), at the cost of massive output files.

But it's not clear whether you're actually looking for transcoding in the first place.

  • "MKV", "MP4", etc. themselves are just container formats – they don't directly define how the video is compressed, only how it's packaged. (The actual video codec would be H.264 or HEVC or VP9; the audio would be AAC or Opus or MP3.)

    It is possible to convert files from one container format to another (e.g. MP4 to MKV) without any transcoding – only by re-packaging (re-muxing) the same data in a different way. In FFMPEG you would do this using the special 'copy' codec, e.g. -c:a copy -c:v copy. This is always lossless and it's as fast as the computer can copy data, but only because it does not transcode anything.

  • But although I said the container formats don't directly define the codec, some of them are compatible only with certain codecs – sometimes for technical reasons, and sometimes just because the "codec ID" or other parameters haven't been agreed on yet. For example, as far as I know you cannot put Opus-encoded audio in an MP4 file, and "officially" you cannot put VP9 video in MP4 either.

    As a result some YouTube download tools deliberately generate MKV files because they have to – they need its greater flexibility regarding which codecs can fit in an MKV file, and either audio or video would need to be transcoded if you wanted to put it into MP4.

  • It is very likely that the problem with Premiere, too, lies not in the container, but in the specific codecs used. For example, if Premiere was incapable of decoding Opus audio, then it couldn't import Opus audio no matter if it's inside an MKV file or a WebM file.

    In these cases, the only way to make it work would be to transcode using a different codec. Sometimes you might be able to keep the video but transcode (or re-download) just the audio. But re-encoding video will be lossly and slow.

grawity
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