Slashdot Mirror

← Back to Stories (view on slashdot.org)

Master Engineer: Apple's "Mastered For iTunes" No Better Than AAC-Encoded Music

Posted by timothy on from the ask-the-master dept.

New submitter Stowie101 writes "British master engineer Ian Shepherd is ripping Apple's Mastered for iTunes service, saying it is pure marketing hype and isn't different than a standard AAC file in iTunes. Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences. Apple or someone else needs to step it up here and offer some true 'CD quality downloads.'"

4 of 312 comments (clear)

  1. hurp by Anonymous Coward · · Score: 5, Informative

    Summary is incorrect. Article says that there was a significant difference between the Mastered for iTunes and CD version, while there was no difference between Mastered for iTunes and a standard AAC track.

  2. Bad summary by tooyoung · · Score: 5, Informative
    The summary implies that the CD version was identical to the Mastered for iTunes version.

    Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences.

    Here is the actual relevant part of the article:

    After his comparison of the three digital music files, Shepherd says there was a sonic difference between the Mastered for iTunes waveform and the CD waveform. He says the Mastered for iTunes and AAC-encoded files didn't reveal any differences

  3. Re:Hey, the pirates can help by gnasher719 · · Score: 5, Informative

    Lets be honest. The only thing you end up losing when going to 16-bit is lost below the noise floor anyway. You use 24 (or better) in the mixing process because that's when it matters.

    Not true. The AAC encoder tries to reproduce its input as faithfully as possible. If you feed it with 16 bit data, that is floating-point data plus quantisation noise, then it tries to reproduce floating-point data plus quantisation noise. Reproducing the quantisation noise is not only pointless (because it is just noise), and takes more bits (because random noise cannot be compressed), or, since the number of bits is fixed, leads to lower quality. If you feed the encoder with floating-point data instead, then it doesn't have to try to encode the noise and has more bits available to encode the actual music.

  4. Duh. by elistan · · Score: 5, Informative
    No surprise. And it's a misunderstanding on the author's part, not a misrepresentation on Apple's part.

    Apple's "Mastered for iTunes" is a set of guidelines about how to turn a master recording into an iTunes-optimized digital file. The author of TFA, however, is talking about taking a CD track and making a compressed version that's as close as possible to the CD track. A CD track is NOT a master file. (We don't want a track that's merely a CD representation - we've heard plenty on /. about how a lot of CD tracks just suck.) "Mastered for iTunes" talks about taking a high-resolution digitial file, like 96/24 or 192/24, and then producing the best possible iTunes Plus file (256 kbps VBR AAC.)

    So of course if you make an iTunes track from a CD track via the "Mastered for iTunes" process, you'll get a 256 kbps VBR AAC that's identical to ripping a CD track to a 256 kbps VBR AAC. However, if you follow Apple's recommendations, quoted here:

    To take best advantage of our latest encoders send us the highest resolution master file possible, appropriate to the medium and the project.
    An ideal master will have 24-bit 96kHz resolution. These files contain more detail from which our encoders can create more accurate encodes. However, any resolution above 16-bit 44.1kHz, including sample rates of 48kHz, 88.2kHz, 96kHz, and 192kHz, will benefit from our encoding process.

    you'll probably get something different, perhaps better, than a CD track ripped to AAC.

    Apple is providing the tools they use to convert to AAC so that sound engineers can preview the product before it goes on sale, but they appear to be the same tools they've been using all along. As I said before, "Mastered for iTunes" isn't a new encoding tool - it's a process workflow. Other recommendations:

    - Apple recommends listening to your masters on the devices your audience will be using
    - Be Aware of Dynamic Range and Clipping
    - Master for Sound Check and Other Volume Controlling Technology
    - Remaster for iTunes [That is, they suggest starting over from the original recordings, rather than send in a file that was mastered with CDs in mind.]