Encoding witth QAAC like CT AAC

[lvqcl]

Uncheck 'No Delay' option. It seems that it's not applicable to HE-AAC.

[tebasuna51]

Seems than the 'No Delay' option only work with AAC-LC.

Sorry, I never test AAC-HE before.

EDIT: like lvqcl say before than me.

[hello_hello]

Edit: Damn! Beaten to the punch twice. I didn't see the thread had a second page.

The "no delay" option can't be used with HE encoding. It's naughty of MeGUI to let you do it. I'll submit a bug report.

Edit: Bug report. https://sourceforge.net/p/megui/bugs/865/

https://github.com/nu774/qaac/wiki/Command-Line-Options

--no-delay
Compensate encoder delay by prepending 960 samples of silence, then trimming 3 AAC frames from the beginning (and also tweak iTunSMPB). This option is mainly intended for resolving A/V sync issue of video.
--num-priming (Experimental)
Set arbitrary number of priming samples in range from 0 to 2112 (default 2112). Applicable only for AAC LC. --num-priming=0 is the same as --no-delay. Doesn't work with --no-smart-padding.

[LeMoi]

OK, last try went fine but the bitrate was too variable, I targeted 64 kbps and I obtained 66 kbps, which can be a problem if a reallt want a specific 700 MB for example. I think I should use CBR to avoid this, or is there another way to have a 'precise' VBR like in video encoding?

[hello_hello]

Which encoding method did you use? For Constrained VBR I think you're setting the minimum average bitrate, but it's allowed to increase, although then it wouldn't be the average bitrate, but that's how Apple seem to explain it. They say it might result in a higher bitrate than ABR encoding.

https://developer.apple.com/library/...1-SUBSECTION11

A 2kbps difference is only about 1.75MB for a 2 hour movie though.

I tried a few quick tests, re-encoding a stereo movie soundtrack, HE-AAC, 64kbps.

ABR - 63.3kbps
CVBR - 66.2kbps
CBR - 64kbps

By the way, QAAC has built in dynamic range compression. I've never used it myself, but you should be able to add it to the custom command line section in MeGUI's encoder configuration. If you do, it might be an idea not to check the normalise option and get QAAC to do the normalising instead. I don't know if it'd change the result. You'd have to test it. The command line option for enabling normalising is -N
There's an example of how to configure the dynamic range compression here:
https://github.com/nu774/qaac/wiki/D...ge-compression
Not that I've used this function either, but you can specify your own downmix matrix. I don't know if MeGUI would complain if the encoding script it creates contains multiple audio channels but the encoder only outputs stereo.
https://github.com/nu774/qaac/wiki/Matrix-mixer

There's a few utilities for "compressing" the audio that don't use standard compression techniques. They work by increasing the volume of the quiet parts rather than compressing the loud bits. I find that works far better as there's no need to adjust the compression threshold for each source. Once you have the "compression" configured the way you like it, it should be fairly set and forget. I use a Winamp DSP courtesy of ffdshow's audio decoder to compress on playback rather than do it when encoding (Potplayer can load them itself). foobar2000 can add DSPs to it's conversion chain so I mainly use it for audio encoding. There's a matrix mixer DSP for downmixing and a WinAmp bridge DSP for loading WinAmp plugins if you want to compress. There's even a plugin for opening Avisynth scripts with foobar2000.

If you're interested, there's a few examples of compression attached to this post, and if you scroll up you'll find links and info on setting up foobar2000. http://forum.videohelp.com/threads/3...=1#post2462994

[LeMoi]

Thanks for your explanations. I use the profile that I showed a snap of it in previous post with CVBR 64 kbps
Actually, i'm doing multitracks mkv, and 2 audio files with 4 MB more can result in a +703 MB file... I know for most people it's not a cotnraint, but for some personal reasons I have to make a CD size file, so it can cause some problems ^^
I think i'll stick with the same profile and I'll just change CVBR to CBR to avoid oversized files, thanks again for your help!
For DRC, I just checked the box in the profile options, but I don't know if it's the same principle you're talking about or not...

[hello_hello]

I think the DRC option simply applies any DRC info that may or may not be present in an AC3 stream. It's there for hardware players to apply DRC for AC3 correctly and I assume it's also applied when re-encoding if the option is checked. Someone else may know if it applies to any other source types. DTS possibly?

[tebasuna51]

@LeMoi
If you want sacrify the quality, using CBR instead CVBR for a 2 Kb/s difference, is your choice, of course is not my advice.

@hello_hello
Is correct your comment.

About DTS: Yes, it can have DRC info when this flag is activated:

DYNF (Embedded Dynamic Range Flag)
DYNF indicates if embedded dynamic range coefficients are included at the start of each subframe. Dynamic range correction may be implemented on all channels using these coefficients for the duration of the subframe

but I only see a few dts's than uses this.

In Dolby Digital streams is mandatory the use of DRC, but encoding with free tools to AC3 (ffmpeg, Aften) is not recommended (bad implemented) at all.

[LeMoi]

Originally Posted by tebasuna51

@LeMoi
If you want sacrify the quality, using CBR instead CVBR for a 2 Kb/s difference, is your choice, of course is not my advice.

If the difference between these 2 settings is audible at these low bitrates, I can do an effort an target a smaller filesize with a smaller video to compensate the oversized audio files

[hello_hello]

I checked to make sure my memory was okay and Wikipedia says a 700MiB CD should hold 703MiB. ImgBurn says 702.8MiB for the CD I looked at, so there's a small margin for error there. https://en.wikipedia.org/wiki/CD-ROM#Capacity

[LeMoi]

Yup, I know that, I generally stop at 702.5 MB max.
I still have to try your script for 6ch, but the quality at 64 kbps seems good compared to my old CT AAC encodings