1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.

    Dismiss Notice

MP3 320 vs AAC 320

Discussion in 'Sound Science' started by salannelson, Aug 29, 2009.
1 2 3
  1. Killcomic
    Tell me about! I think that's probably the reason why many people have issues with lossy formats.
    It also explains why music from the 70's and 80's sound phenomenal with lossy encoding, it's just that they are mastered better!
    bigshot likes this.
  2. Steve999
    Thanks for doing that. That helps confirm the source of some problems I've had with AAC files in Windows but that do not occur on my Macbook or my Ipad or Apple TV with the same files. In Windows I had to just play around with the sound settings for HOURS to get rid of the clipping. I still don't know what worked, I just got frustrated and went around irrationally clicking and unclicking on sound control panel and itunes settings. Happily listening to my AAC files on my windows computer right now. I kind of confirmed it was digital clipping because in Windows I would go into Itunes-View-Show Equalizer and as I turned the Itunes digital amp (to the left of the Itunes Equalizer) higher I would get more of the clipping. I set the amp to lower and lower and the clipping went away. I clicked various boxes and was able to get the Itunes amp setting back up to neutral. I've left the Itunes EQ "on" and on the manual setting at flat and the Itunes amp to neutral (0 db). I'm scared to change anything, such as turning the Itunes EQ off, lest Windows should try to do something "smart" on its own and make the clipping come back. I kind of look at it as Apple and Microsoft being a little too indifferent or uncooperative as to how well Itunes works in Windows, though that's just a guess.
    Last edited: Dec 16, 2018
  3. Steve999
    Since you are in MediaMonkey and using Nero I'm guessing you are are in Windows? I am just trying to see how similar your problem was to mine. Do you have a mac product to try for playback of the files that were clipping? If so I would be curious if those hot AAC files still clipped on a Mac computer or device. Based on my tinkering I would guess not. I think as suggested it really could be the case--that this is why some people complain of digital harshness with lossy files, because of software and operating system problems that cause borderline to overt clipping.

    Again, for anyone jumping in this thread late, Kilcomic has solved his problem by rationally reducing the digital level before encoding from FLAC to AAC and I have solved it or a similar problem by spending hours irrationally goofing around with Windows and Itunes sound settings.
    Last edited: Dec 16, 2018
  4. castleofargh Contributor
    isn't the apple encoder supposed to reduce the gain after checking for intersample clipping so that everything is cool for the encoding and for the playback? I'm still using mp3 like a caveman, but I thought I read something like that once. but maybe it was about a specific AAC encoder? IDK.

    personally I got pretty paranoid about intersample clipping and clipping in general, and I have 2 different points along the digital chain to tell me if I happened to clip, so I can mess around with EQ and DSP without panicking.
    a free VST that does a fine job for me is DPmeter. the latest version DPmeter III, might require to RTFM to avoid messing up, so those who know they will never read the PDF, maybe get the first or second version of that VST if it's still somewhere on the web. I like that VST because when it clips, the little bars stay on even after several songs. so you don't actually have to keep it open and watch some VU meter all the time like a crazy person.
    my EQ also shows that something had clipped, but it's a pricey app so better stick to free stuff.

    @Steve999 more than apple vs windows, the difference for you could have to do with the players and audio paths settings. like in foobar, the values are 32bit floating, which won't really care if some value goes a little above 0dB. but after that, if you get into integer stuff(which is likely), then anything above 0dB becomes 0dB. oops. or it could be something super dumb like a digital gain or an EQ somewhere. either creating the clipping issues, or saving you from it with an attenuated gain by default so that you won't clip even when you boost a frequency in the EQ. effectively giving that much digital headroom to all signals. there are even DACs that are built to have a few dB of headroom for intersample clipping(not the norm though).
    ultimately creating a loop from your DAC's output into the input of a soundcard and checking that some full scale sines don't clip from your player, would be a decent way to check if something weird is going on with gain and/or oversampling. in foobar when using replaygain, you have the option to prevent clipping according to peak. and if you scan with some oversampling(very CPU hungry!), the accuracy of those peaks will improve. or you could just set up stuff to have like -3dB in the "preamp", and just forget 99.9% of intersample clipping issues. this is really one of those stuff where we do have 20 ways to skin a cat.
    now if the file is encoded with clipping into it, well that's that.

    I always wonder how many people got into purchasing ludicrous gears, apps, and file resolutions thinking that everything else sounded like crap because they were clipping the signal without knowing? after all, the "bit perfect" frenzy on audio forums only makes it more likely to get clipping. I have no doubt that a good amount of the people saying that lossy formats sound bad would change their mind if they simply were more aware of digital levels and how things work. because it is absolutely true that a lossy file is likely to have higher intersample clipping than higher resolution files. but nobody is forced to actually convert that potential into real clipping.
  5. bigshot
    It's rare, but I've noticed that some tracks in iTunes tend to get a tiny bit hotter after encoding to AAC. But I don't notice any clipping.
    Last edited: Dec 17, 2018
  6. Killcomic
    I use my iPhone as my source and that's where I noticed the issue. Well, to be honest, I noticed the issue when using my old Fiio X1, but it was also present in my iPhone.
  7. Killcomic
    Unfortunately I would need to go through ALL my songs and adjust the gain manually to compensate. It's about 14,000.
    I wouldn't say it's a Windows issue, but certainly one of encoders.
  8. bigshot
    Is the clipping burned into the file or is it just clipping on playback? If it’s just on playback you can use one of those gain balancing plugins across your whole library.
  9. Killcomic
    I did a raw conversion again, changed the encoded file's gain value in Foobar and WHAM! Clipping is gone!
    Mind you, I'm not sure how to go about this as I need this to be done automatically and repeatably without completely messing my 14,000+ library of music.
    Well, the automatic conversion done by Foobar seemed to do the trick and I do have my music backed up so... I dunno. I'll have to work up the courage to do this.
  10. bigshot
    It's just a flag in the file. It doesn't change the sound part of the file at all.
  11. Killcomic
    Well, I figured that so I got Foobar to do the entire library. The problem is that when I encode, all the gain level data gets thrown out.
    The encoding is done straight to my iPhone so once it's in there, I cannot change it.
    However, I think I found a setting that helped. Don't ask me how or why, but if I set the contained to m4a instead of AAC, and still use AAC to encode, then choose mid/side stereo, instead of the default full stereo, it seems to do the trick.
    I believe that the encoders did not have the best defaults for what I was looking for.
  12. Steve999
    That sounds so frustrating. I am assuming the files are not clipped themselves. . . is there any way to check? Just throwing something out there. . . maybe when the perceptual encoding is in mid/side stereo instead of full blast both channels there is a little more headroom in the louder channel in case of software problems? Since I was having problems on non-apple devices with apple-encoded files, I don't know how you get around files that are not apple AAC encoded files but have problems on Apple devices. I know the feeling and how frustrating it can feel though.
  13. Killcomic
    Well, I did an ABX test with the encoded and FLAC file and got 7/16 right. So I guess they are pretty much indistinguishable now!
  14. bigshot
    Good news!
  15. Killcomic
    Oh indeed! Just think of all the extra space I have now!
1 2 3

Share This Page