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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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evereux
post Apr 20 2012, 07:24
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Can't you use a setting that won't be transcoded by YouTube? That will always be the best option.

By "lossless" do you mean "perceptually transparent"?
Lossless = impossible with the format you are choosing.
Perceptually transparent? is something only you can answer.


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zerowalker
post Apr 20 2012, 08:29
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QUOTE (evereux @ Apr 20 2012, 08:24) *
Can't you use a setting that won't be transcoded by YouTube? That will always be the best option.

By "lossless" do you mean "perceptually transparent"?
Lossless = impossible with the format you are choosing.
Perceptually transparent? is something only you can answer.



Sadly it always re-encodes everything (atleast as i know).

And correct, that is what i meant, transparent.
I want to know from when itīs transparent in general:)
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LithosZA
post Apr 20 2012, 08:33
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I am not sure that is possible, but try to upload a format that YouTube supports so that YouTube won't transcode it.
It seems like MP3 is out of the question when looking at the table at: http://en.wikipedia.org/wiki/YouTube
There are no open source AAC encoders that can make an acceptable sounding file unless the bitrate is extremely high. If you want to encode to AAC use something such as QAAC or Nero's AAC encoder.
OGG Vorbis might be the best option, but you will have to mux the Vorbis stream into a WebM container before uploading I think(To avoid transcoding).

Edit: If YouTube is always going to transcode then I think uploading a FLAC might work the best. If YouTube can transcode from FLAC that is.

Another Edit: To me 192 Kbps MP3 is transparent, 128 Kbps Vorbis is transparent, 128 Kbps AAC is transparent(depending on the AAC encoder). I haven't tested all the bitrates for FAAC, but it definetly is not transparent even at 192 Kbps.



This post has been edited by LithosZA: Apr 20 2012, 08:43
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zerowalker
post Apr 20 2012, 08:39
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QUOTE (LithosZA @ Apr 20 2012, 09:33) *
I am not sure that is possible, but try to upload a format that YouTube supports so that YouTube won't transcode it.
It seems like MP3 is out of the question when looking at the table at: http://en.wikipedia.org/wiki/YouTube
There are no open source AAC encoders that can make an acceptable sounding file unless the bitrate is extremely high.
OGG Vorbis might be the best option, but you will have to mux the Vorbis stream into a WebM container before uploading I think.



But is it even possible at all to not let it transcode;O?
As Audio is one thing, but the video is another, as there is so many settings, and they havenīt really made any (Use this settings) thing.
I think that even if you download the Webm file, and reupload, it will reencode it.

As Youtube is ratehr wasteful, letīs say you upload an 1080p movie.

It will than be 1080p mp4
720p mp4
480p mp4
480p webm
360p mp4
360p webm
240p mp4
240p webm

Donīt remember if they have set up webm on 1080p and 720p yet.

But you se, they re-encode in so many forms, so i think they reencode no matter what;O

So i need to Encode so that the Transcode will be as lossless as possible, but at the same time not using much space as Flac, as itīs not worth it really.
Thatīs the reason for Vorbis as it seems to be the "best" in terms of size/quality.

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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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zerowalker
post Apr 21 2012, 04:00
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QUOTE (slks @ Apr 20 2012, 22:57) *
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.



Yeah my thought are the same, as itīs another transcoding, more Quality should decrease the loss.
Yeah but the problem is that my internet is pretty slow, so Vorbis Q7.5 and FLAC is a nice difference, thought as you say, my files are so big that it really doesnīt matter much.
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