FLAC vs M4A

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dypsis
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Joined: Wed Apr 30, 2008 9:51 pm

FLAC vs M4A

Post by dypsis » Mon Jul 02, 2012 4:36 am

I have been ripping to FLAC for years, but I have recently been reading a bit about M4A.

There seems to be a lot of confusion and conflicting information out there about the M4A format.
I have seen some say it is lossy, and some say it is lossless.

If M4A truly is lossless, then that would make FLAC a redundant format given the fact that M4A tracks are roughly the same size as MP3, which is a lot smaller than FLAC.

So, can someone shine some light on my queries about the M4A format? Is it a lossless format, and is the sound quality as good as FLAC?

Anamon
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Re: FLAC vs M4A

Post by Anamon » Mon Jul 02, 2012 6:39 am

When talking about "audio formats" it is important to make the difference between codecs and containers. M4A is a container format. A container is a method of storing audio streams in a file. Per se, it does not say anything about what compression has been used to encode the audio stream. In particular, M4A is popularly used for both AAC (lossy) and Apple's ALE/ALAC (lossless) codecs. So just going by the filename, you can't tell whether the audio has been stored lossy or losslessly.

What I can say with 100% certainty though is that if your files are even within the broader region of the size of an MP3 file, then they are lossy. The compression you get with FLAC is near-optimal. There is no alternative codec (with sensible encoding and decoding times) that will give significantly better compression than FLAC, and it's not likely to ever happen.

If you want your files in lossless quality, it is up to you what you decide to do. I keep everything in FLAC since it has always been an open format (that is also supported by my portable player), while ALAC is used practically only by Apple products. Compared to those two, all other lossless codecs are far less widely supported. The good thing about lossless though: if you ever think you made the wrong choice, you can always convert your library without any compromise in quality.

You can also check out Wikipedia's articles on the MPEG-4 Part 14 (that's M4A) container format, and the Advanced Audio Coding (AAC) or Apple Lossless (ALE/ALAC) codecs respectively.

dypsis
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Re: FLAC vs M4A

Post by dypsis » Mon Jul 02, 2012 1:49 pm

Thanks for the excellent reply, Anamon.

I have since found out that the M4A iTunes tracks are lossy AAC (LC).

Solitaire001
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Re: FLAC vs M4A

Post by Solitaire001 » Wed Sep 05, 2012 9:21 pm

Anamon wrote the following as part of a post:
Anamon wrote:If you want your files in lossless quality, it is up to you what you decide to do. I keep everything in FLAC since it has always been an open format (that is also supported by my portable player), while ALAC is used practically only by Apple products. Compared to those two, all other lossless codecs are far less widely supported. The good thing about lossless though: if you ever think you made the wrong choice, you can always convert your library without any compromise in quality.
This is one of the main reasons that I've begun re-ripping my music collection in FLAC. Although my player doesn't support FLAC, I can easily convert the songs for it into one of the formats that is supported by my player and at the quality level I choose without having to re-rip my CDs. The fact that FLAC is an open format is a strong advantage for maintaining my library in that format, and the dropping cost of large hard drives (I can purchase a 1TB external hard drive for less than $100) makes the size of FLAC files less of an issue.

Another advantage of ripping to FLAC is that I only have to tag my files one time. In the past, when I re-ripped my tracks (such as when I obtained a better encoder), I ended up having to re-input and then check and correct the track information. Although I can transfer some of the information from the old songs to the new ones, it still takes time. Now, I rip to FLAC and then tag the files once. When I convert the files for use on my player, the tag information is carried over to the converted file. This is also an incentive to add more information (such as the composer credits) to my song's tags.

fultronics
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Re: FLAC vs M4A

Post by fultronics » Thu Dec 19, 2013 12:27 pm

Thank you for the explanation. I was wondering if the m4a files I received were lossless or not. They were averaging a bitrate of 313 kbps. I wanted to convert them out of m4a but maintain the highest bitrate possible.
Instead of MP3 CBR 320 (higher than the original) or VBR 256 (V0 highest manual rate in MM- lower bitrate than original) I went with FLAC at 0 compression. Here’s what’s odd, a 313 kbps (10.3 MB) [44 100 Hz] m4a converted to 891 kbps (28.9 MB) [44 100 Hz] FLAC.
So if m4a isn’t a lossless compression file type how did I end up with a larger FLAC than the original m4a? Did I unpack or decompress the m4a or is my monkey FLAC converter doing the best it can with the available settings (adding file size and bitrate that isn’t actually original content)?
There is the possibility that I’m completely misunderstanding… if so, just Lemmy know.
Lastly, There’s so much to love about Media Monkey; I really appreciate the knowledge base that willingly shows up to the forum to help out.
><{{{(:> Fish, Eat Fish <:)}}}><

Lowlander
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Re: FLAC vs M4A

Post by Lowlander » Thu Dec 19, 2013 12:48 pm

When converting to a higher bitrate format (FLAC is higher bitrate) you'll see a higher bitrate on the converted copy, however the file is of no better quality (actually can be worse (unless lossless to lossless conversion)). Which means you're just ending up with a larger file without any better quality. You can never upgrade from a lower quality to a higher quality copy as the information required isn't available in the lower quality file. You'll need to recreate the file from a higher quality source (like re-ripping from CD).
Lowlander (MediaMonkey user since 2003)

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