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Encoding for Transcoding
zerowalker
post Apr 20 2012, 05:22
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Okay not entierely sure you are supposed to ask this, but i think i can.
I am currently using Oggenc2.87 using aoTuVb6.03 for encoding audio from Gameplays for uploading on youtube.
i use 7.5 Q.

My question is,

What Q setting is supposely "lossless", as i want youtube to get as high wuality as possible (of course Flac is better, but not worth it here).
And Youtube uses 192 AAC or something.


Sorry if this isnīt supposed to be asked, i know you canīt ask what is "Best" and such, but the Q setting doesnīt need to be specific,
Just some general knowledge, as my ears myself arenīt my most trusted tools.

Thanks:)


Edit: Of course if you want to recommend a more suitable codec, please do.
I am using Vorbis as i like Open Source, and i think itīs good, but i donīt know if itīs better than AAC or not.

This post has been edited by zerowalker: Apr 20 2012, 05:32
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slks
post Apr 20 2012, 21:57
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Well, with my own tests of Vorbis, I got transparency at about -q 4 or -q 5. But that's going directly from lossless to Vorbis. When you upload stuff to YouTube, you're not in control of the entire signal chain, and it goes through an extra transcoding step. Lossless -> Vorbis -> AAC (or whatever YouTube uses). So even though Vorbis by itself is probably transparent at -q 4, it wouldn't hurt to keep using -q 7 or even -q 10 to give yourself a little extra headroom for the transcoding YouTube does.

Now the best thing to do, quality-wise, would be to use FLAC (assuming YouTube supports FLAC uploads). Once the video gets to YouTube, how they encode it is out of your hands. So really the only thing you can do to maximize quality is to feed YouTube the highest possible quality to work with - which means lossless. It might take a few extra minutes to upload a video, but I'd say its worth it.

It actually won't make the overall A/V stream much larger. I'm not sure what kind of bit rates you're using on your videos but it's likely to be several megabits... lets say 3,500 kb/s. Going from high-bitrate Vorbis to FLAC is only going to add an extra ~400 kb/s on top of that... something like an 11% increase. You only need to upload once, so just take the extra couple minutes of upload time, if you want maximal audio quality.


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