HydrogenAudio

Lossy Audio Compression => AAC => AAC - General => Topic started by: cyberandroid on 2018-09-10 16:00:29

Title: highest cbr aac encode rate?
Post by: cyberandroid on 2018-09-10 16:00:29
What is the highest cbr bitrate possible with an aac encoder?

Is it 529kbps/576kbps with enc_fhgaac.dll?

What other encoders can do similarly high bitrates?
Is Nero capable of exceeding 400kbps (i am finding conflicting info)?

theoretically the aac format supports 1152kbps 96khz - can any encoder do this?

i want to run some tests against youtube's content normalization using aac gain
youtube is now recommending 384kbps aac-lc for stereo content

so i can assume that youtube's aac implementation will take any file supported by the standard (as 384kbps is recommended)
this also insinuates that youtube does not want audio resampled before upload (as 384kbps is max rate for 32khz audio and happens to make sense as a sensible minimum for 96khz)

also fyi youtube supports mkv containers with flac
Title: Re: highest cbr aac encode rate?
Post by: Deathcrow on 2018-09-12 10:28:36
I'm not 100% sure, but I'm quite convinced youtube will transcode any AAC file you upload. I don't think it will ever take the original bitstream as is, even if it has to transcode from AAC->AAC

So I'm not sure I understand what you are trying to achieve here. Why are you talking about 96khz audio? Youtube will just resample it to 44.1 or 48khz depending on codec.
Title: Re: highest cbr aac encode rate?
Post by: cyberandroid on 2018-09-12 16:56:43
youtube transcodes everything.

i just want to know what encoders will go up to 529kbps/576kbps respectively

youtube will accept up to 192khz but once you exceed 48 you should be utilizing flac in a mkv container or pcm (wav) and uploading 24bit if possible

can any encoder do full spec aac 1152kbps at 96khz?
if it can do that then we can assume it will do 576 no problem.

youtube re-encodes everything, but subjectively the sound is better if you feed it hd audio. upsampling prior to upload is worse then just uploading lossless at whatever native rate.
Title: Re: highest cbr aac encode rate?
Post by: saratoga on 2018-09-12 23:34:03
youtube will accept up to 192khz but once you exceed 48 you should be utilizing flac in a mkv container or pcm (wav) and uploading 24bit if possible

You shouldn't be using excessive sampling rates like that, so rather than relying on youtube to downsample them for you, you should just use 48k in the first place. 

Rather than use very high bitrate lossy, you can just use FLAC, however there isn't a lot of point compared to something like 256k AAC anyway so I would use that if you can't go for the full lossless bitrate.
Title: Re: highest cbr aac encode rate?
Post by: polemon on 2018-09-14 00:29:44
youtube will accept up to 192khz but once you exceed 48 you should be utilizing flac in a mkv container or pcm (wav) and uploading 24bit if possible
[…]
youtube re-encodes everything, but subjectively the sound is better if you feed it hd audio. upsampling prior to upload is worse then just uploading lossless at whatever native rate.
I'd suggest tuning for the output/delivery system if you know what you're doing, and not relying on the boilerplate systems used at Youtube. Keep in mind, those are first and foremost for quick'n dirty MPEG-H optimized delivery of content uploaded directly from a webcam or things like Final Cut Pro. If you know what you're doing, you should tune your finished product to it, and not rely on the un-tuned systems which are pretty much just a black box to everyone. For instance I'd wonder if the bit-depth conversion at google is doing a well enough job converting from 24bit/s or higher down to 16bit/s. Let youtube deal with downconverting further, sure. But you should still tune the finished product for the chosen delivery platform, anyway - if you can help it at all.