afcovert uses the superior inbuilt AAC converter. FFmpeg can do this as well with the right arguments but you have to dig them up and the quality is capped to a lower value than you can get with afconvert.
I have three reasons: when using a good encoder (Core Audio, FDK or Nero) it's a quality-wise better lossy format than MP3, it's smaller than FLAC which matters for storage footprint, and unlike Opus and FLAC it's supported pretty much everywhere. At some point Opus will reach the same level of adoption and that's the point where I'll make the switch from AAC, because Opus is evidently a better lossy encoder per same bitrate.
I like to load WAVs on my iphone if lossless uncompressed available. AAC is the next highest quality supported lossy compression file in apple music app. From my understanding they won’t ever go to flac or opus because don’t want software decompression.
I like opus on VLC for youtube-dl rips but if I’m buying music I want lossless uncompressed.
ffmpeg offers a few different encoders for many of its supported audio/video formats, and the result depends on what encoder you tell ffmpeg to use. It does not have support for using Core Audio on macOS but it does offer FDK AAC, which is one of the better AAC encoders available today - though not nearly as good as the one available in Core Audio.
Do you have any sources/informations on an objective comparison of encoders quality ?
Way back then (iPod era), I made an exposé for a science exam (small paper), proving that AAC was indeed better than MP3 both subjectively and objectively at most bitrates. This is how I got introduced to Fourier transforms and the likes; it was very interesting to see that you can literally "see" the difference in quality on the encoded waveform output.
But I just used the default encoders on the Mac and I didn't think about going in deep into encoder comparisons at the time.
Does it matter that much? From what I know, it just about properly programming a math spec, with some tricks but I wonder if that makes that much of a difference.
In any case, above 256kbps it takes a very skilled listener to correctly identify encoded music. Apple has some useful tools for that, particularly AU Lab that allows you A/B testing of tracks with on-the-fly encoding.
https://www.apple.com/apple-music/apple-digital-masters/
One source would be the Hydrogen Audio forums where there are regular scientific comparisons - PSNR etc. instead of blind listening tests - between various encoders and formats. Apple's AAC encoder consistently comes out well above anything MP3, best of all the AAC encoders, and up at the absolute top together with Opus which produces a bit better results per same bitrate.
> Does it matter that much? From what I know, it just about properly programming a math spec, with some tricks but I wonder if that makes that much of a difference.
It does matter a lot and the difference can be staggering. Producing the audio bitstream is a case of both effectively analyzing the original input and programmatically expressing the waveform as correctly and as efficiently possible. Two excellent examples: the old MP3 encoder Xing, which compared to LAME produces very poor material even at higher bitrates, and one of the earliest open-source AAC encoders, FAAC, which also renders a very poor product. A lot of "early adopters" got bitten by FAAC and many of them still stubbornly cling to the misunderstanding that AAC is a worse format than MP3.
>From what I know, it just about properly programming a math spec
Incorrect. The specification only concerns the bitstream and the decoding. Encoders are free to do whatever they want, as long as they produce a valid bitstream.
afcovert uses the superior inbuilt AAC converter. FFmpeg can do this as well with the right arguments but you have to dig them up and the quality is capped to a lower value than you can get with afconvert.
Isn't -c:a aac_at the same? And then designate bitrate?
There's no reason to use AAC when we have both OPUS and FLAC.
I have three reasons: when using a good encoder (Core Audio, FDK or Nero) it's a quality-wise better lossy format than MP3, it's smaller than FLAC which matters for storage footprint, and unlike Opus and FLAC it's supported pretty much everywhere. At some point Opus will reach the same level of adoption and that's the point where I'll make the switch from AAC, because Opus is evidently a better lossy encoder per same bitrate.
3 replies →
I like to load WAVs on my iphone if lossless uncompressed available. AAC is the next highest quality supported lossy compression file in apple music app. From my understanding they won’t ever go to flac or opus because don’t want software decompression.
I like opus on VLC for youtube-dl rips but if I’m buying music I want lossless uncompressed.
ffmpeg offers a few different encoders for many of its supported audio/video formats, and the result depends on what encoder you tell ffmpeg to use. It does not have support for using Core Audio on macOS but it does offer FDK AAC, which is one of the better AAC encoders available today - though not nearly as good as the one available in Core Audio.
Do you have any sources/informations on an objective comparison of encoders quality ?
Way back then (iPod era), I made an exposé for a science exam (small paper), proving that AAC was indeed better than MP3 both subjectively and objectively at most bitrates. This is how I got introduced to Fourier transforms and the likes; it was very interesting to see that you can literally "see" the difference in quality on the encoded waveform output.
But I just used the default encoders on the Mac and I didn't think about going in deep into encoder comparisons at the time. Does it matter that much? From what I know, it just about properly programming a math spec, with some tricks but I wonder if that makes that much of a difference.
In any case, above 256kbps it takes a very skilled listener to correctly identify encoded music. Apple has some useful tools for that, particularly AU Lab that allows you A/B testing of tracks with on-the-fly encoding. https://www.apple.com/apple-music/apple-digital-masters/
One source would be the Hydrogen Audio forums where there are regular scientific comparisons - PSNR etc. instead of blind listening tests - between various encoders and formats. Apple's AAC encoder consistently comes out well above anything MP3, best of all the AAC encoders, and up at the absolute top together with Opus which produces a bit better results per same bitrate.
> Does it matter that much? From what I know, it just about properly programming a math spec, with some tricks but I wonder if that makes that much of a difference.
It does matter a lot and the difference can be staggering. Producing the audio bitstream is a case of both effectively analyzing the original input and programmatically expressing the waveform as correctly and as efficiently possible. Two excellent examples: the old MP3 encoder Xing, which compared to LAME produces very poor material even at higher bitrates, and one of the earliest open-source AAC encoders, FAAC, which also renders a very poor product. A lot of "early adopters" got bitten by FAAC and many of them still stubbornly cling to the misunderstanding that AAC is a worse format than MP3.
1 reply →
>From what I know, it just about properly programming a math spec
Incorrect. The specification only concerns the bitstream and the decoding. Encoders are free to do whatever they want, as long as they produce a valid bitstream.
2 replies →
Today OPUS is on par of AAC if not better. We aren't at the MP3/OGG times.
3 replies →
It does. -c:a aac_at uses Core Audio (_at means AudioToolbox).