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Audio Format Transcoding for Compatibility? 64

Posted by Cliff from the media-(format)-manipulation dept.
brandorf asks: "With the multitude of compressed audio formats that are available today, (MP3, Ogg, AAC, and FLAC to name very few) our music libraries start to spread across quite a few different formats. While this isn't a problem for desktop/media PC use, as programs like Winamp or iTunes have plugins available for almost every format. However, when it's time to start using a portable unit, it's unavoidable that some files will get transcoded. Have there been any studies or experiments as to how similar the codecs really are? Will transcoding from Format A to B sound worse than going from A to C? What's your experience with this?"
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Audio Format Transcoding for Compatibility? More

Audio Format Transcoding for Compatibility?

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  • Hydrogen Audio have tested this (Score:5, Informative)

    by doofusclam ( 528746 ) <slash@seanyseansean.com> on Wednesday April 06, 2005 @02:56PM (#12157278) Homepage
    http://www.hydrogenaudio.org/forums/index.php?show topic=32440 [hydrogenaudio.org]

    The site insists on proper ABX tests too, not some thirteen olds insisting they can tell the difference between FLAC and Monkey's Audio codecs.

  • If you're that concerned... (Score:4, Insightful)

    by Anonymous Coward on Wednesday April 06, 2005 @02:59PM (#12157332)
    Use a lossless format for archival purposes (any format really since you won't use it on your portable), then use MP3 for everything else. MP3 is the only thing that pretty much every portable can play. OGG and Windows Media are a close second but I would never consider Windows Media format.
    • If you use any reasonable lossy codec at a high enough quality setting, it's essentially the same as a lossless codec, and you still save space compared to the lossless (bit accurate) codecs.

      • Re:lossy != bad (Score:3, Insightful)

        by Paladin128 ( 203968 )
        Essentially the same on a $20 boom box maybe. Listen to it on a decent hi-fi. On my sub-$1000 rig (Yamaha HTR-5150 reciever, a pair Boston Acoustic CR-9's), lossy sounds noticeably worse than non-lossy. With my Linux box as the audio source, and an S/PDIF-out (so you can't claim it's my crappy sound card's fault for a shitty signal), if I'm actually listening (as opposed to having music just "in the background" for a conversation) I can certainly hear the difference between 160kbps Vorbis and FLAC. Hell, I

        • Re:lossy != bad (Score:2, Insightful)

          by cahiha ( 873942 )
          On my sub-$1000 rig (Yamaha HTR-5150 reciever, a pair Boston Acoustic CR-9's), lossy sounds noticeably worse than non-lossy.

          That statement makes no sense whatsoever. Just digitally adjusting the volume down a little on your recording is "lossy" coding, since you can't recover the original signal from the reduced volume signal. Does that sound worse? I don't think so.

          The point is: if you set the bitrate for a lossy codec high enough, you won't hear a difference. If you set it even higher, you won't he
          • That's why my sound card doesn't even have the capability of adjusting the volume on the way out. The only volume adjustment is done by the knob on my reciever. The sound card, in my equation, makes no difference.

            I'm sorry, I use LAME and the reference vorbis libraries for encoding. There is NO influence on the part of the sound card of the output signal; that's all software.

            Do you even know how MP3's work? They look at a wave, and try and identify series of waves that "mask" other series of waves when pr
            • Do you even know how MP3's work? They look at a wave, and try and identify series of waves that "mask" other series of waves when processed by the human ear, and throw out the masked waves. This only works so well...

              It can work arbitrarily well, depending on the bitrate. A good codec doesn't throw out coefficients if it doesn't need to. So, if you set the bitrate high enough, then it will code all the coefficients and you shouldn't hear any difference (even though the output may still not be bit-identic
              • Meh... I've listened to MP3's that are sampled at upwards of 320kbps... they sound better, but still like crap.

                It's not that I'm not affected by masking -- it's that everyone is affected by masking slightly differently. Also, particularly in lower frequencies, there are often frequencies that you may not hear, but you will feel. For instance, the range I have the most trouble with is the male human vocal range; if there are two people speaking in my vicinity simultaneously, even if they are at different le
      • For archiving and trans coding yes lossy is bad. If you trans code from one lossy format to another lossy format you get the worst of both formats.
        With Harddrives so cheap I would be tempted to rip everything to FLAC and then convert to ogg or MP3 for my portable player.

  • Quality Loss (Score:5, Funny)

    by Sebilrazen ( 870600 ) <blahsebilrazen@blah.com> on Wednesday April 06, 2005 @03:01PM (#12157352)
    I've noticed significant reduction in lows and an unsettling amount of distortion when I go from vinyl to wax cylinder.
    • Simple solution: stop carving your cylinders out of ear wax.

    • Re:Quality Loss (Score:5, Insightful)

      by dstone ( 191334 ) on Wednesday April 06, 2005 @04:44PM (#12158681) Homepage
      I've noticed significant reduction in lows and an unsettling amount of distortion when I go from vinyl to wax cylinder.

      Run a green, felt-tipped pen around the outside of the wax cylinder. It will restore the low frequencies lost from vinyl. I would describe the restored sound as quite earthy, rather than airy though. If airy is what you're going for, I suggest making make two light applications of green felt-tipped marker, rather than one heavy one. This however, could result in very cinnamon flavored mids and highs though, so be careful. In a pinch, you could use a black felt-tipped pen, but don't just use any old Sharpie. Use something really expensive, preferably immediately after writing a page of taoist scriptures on parchment paper. Northern taoist is fine, but southern taoist would be better, especially if you listen to a lot of jazz. Unless it's smooth jazz. Oh, and insulate yourself with 24K gold arch supports before trying any of this, otherwise the earth's own vibrations could mellow your high frequencies, resulting in distinctly cedar-flavored vocals.

  • Transcode? Junk in, junk out (Score:3, Insightful)

    by anacron ( 85469 ) on Wednesday April 06, 2005 @03:10PM (#12157478)
    If you have a lossless source, the quality of the derived audio should be as good as an original rip of the CD itself. That's the whole point of lossless encoding. If you're going from lossy->lossy, then any transcoding will introduce garbage, but how much garbage depends on how good the original source is. .anacron

    • Re:Transcode? Junk in, junk out (Score:1, Informative)

      by Anonymous Coward
      To elaborate on anacron's response. For archive purposes, if possible you want to save in a lossless format like FLAC or APE.

      As long as your original is in a lossless format, then you can transcode to a lossy format (like MP3, AAC, or OGG) for portable players without excessive degradation.

  • Well, in the real world, I'd say the best source format is the one you got, and the best target format is the one you need. Duh.

    But still, on a theoretical level, the question IS interesting. The hydrogenaudio link above only compares very few codecs, and I'd especially like to hear more about codecs I am forced to use (like WMA or RA), since all OGG etc. files I've got are encoded by myself, and I would have had the chance to encode to the desired target format right away.

    On a somewhat related note,

  • FLAC, ALE, etc. are the way to go (Score:5, Funny)

    by Anonymous Coward on Wednesday April 06, 2005 @03:27PM (#12157733)
    Seriously. Encode your music in a lossless format, then transcode it to whatever lossy format you use on the go. Sure, it's much bigger, but it will be bit-for-bit accurate! Even if you can't tell the difference on your $50 computer speakers and bundled iPod headphones, you can feel good because you know it's better.

    Also, it will get you laid.

    Love, your hard drive manufacturer.

  • easy.. (Score:3)

    by polyp2000 ( 444682 ) on Wednesday April 06, 2005 @03:31PM (#12157789) Homepage Journal
    encode from mp3 to flac ... ;)
  • I encode .flacs and CDs straight to .oggs and most everything else I've ended in with my collection is in MP3. For the stuff that really matters, most is in the 256-320/k range CBR. The oggs I encode are all 350 ABR, for what its worth sounds really, really close to a CD and certainly better than MiniDisc. I'd love to just store nothing but FLAC, but I would need to start looking at quadrupling my file server's capacity, which would put me over a terabyte. Also since I run slimserver on my file server a
    • Also, to answer your question more fully, just pick a good quality format you wish to use (like if just MP3 is ok for you, use MP3) and when you transcode set it to the highest settings possible. Personally I think ogg is the better format, but it limits your choices as far as portable players and such go. Even OGG --> MP3 transcoding is not all that bad because you are starting with a better source file than MP3. WMA is also a superior format than MP3, so pretty much anything is going to be better th
  • I back up my cd's to ogg at a high bitrate, usually VBR averaging about 256kbit. I do all my transcoding from those 256kbit masters. On occasion I need to fit them on a small mp3 player or pack a bunch onto an mp3 cd, in which case 128 is desirable. I can barely hear distortion at 128, and only with a few songs.
    • Saying "Aim high" is a bit of a joke compared to lossless formats, but I do pretty much this same thing. I rip to high VBR MP3, 324 kb IIRC. And then for my Axim with it's 1 GB SD card (over half of which is my local mirror of Wikipedia!) I transcode (using GX::Transcode, great free [or shareware, not sure] app for Windows) to 128 bit ogg. I personally don't notice any difference between transcoding and just ripping to OGG from CD or transcoding from FLAC, but I'm no extreme audiophile- but in general, c

  • Why not just keep lossless copies? (Score:4, Interesting)

    by zoeblade ( 600058 ) on Wednesday April 06, 2005 @04:09PM (#12158249) Homepage

    Hard drive space is plentiful. Just rip everything to a lossless format, such as FLAC, or even .wav or .aiff if you can't be bothered with the hassle, then make a convenient shell script to convert everything into another format as and when required. That way, you get the best sounding MP3s or Ogg Vorbis files with none of the bad side effects of transcoding, and as soon as any given codec is improved or replaced by a better one, you won't have to worry about not taking advantage of the shiny new algorithms.

    • Re:Why not just keep lossless copies? (Score:1, Insightful)

      by Anonymous Coward
      Hard drive space is plentiful. Just rip everything to a lossless format, such as FLAC, or even .wav

      A WAV file is about 10 times bigger than your average mp3, and lossless encoding can get down to about 5 times bigger. So taking a purely hypothetical Music directory of say 32.4 GB (no really, i've listened to ... most... of it) that leaves 324GB in WAV or 162GB in FLAC.

      Hard drive space suddenly doesn't look quite so plentiful, even for music collections of a saner size.
  • Maybe you need a structure for your audio files.

    I assume that most of your recordings are music (vs. spoken words or whale songs.). Where are you getting the files from? If you are encoding them yourself, then pick FLAC if you've got the space. Lossless will guarantee that you don't get artifacts, at the expense of storage space. If are ripping from CD, you'll want to have as high a quality as possible - unless you have a small collection, you won't want to go through the ripping process several times. I
  • But what tools do you use?

    I have a load of AAC from iTunes (ok, pymusique, thanks chaps) and I'm havinga hard time getting mencoder or something to convert them to mp3.

    I know its a doddle and I'm looking in the wrong place, so it would be nice to see what command line tools (and spells of tools) folk are using to transcode?

    Sam
  • Is there a way to pop a (paid for) DVD, DVD-A, SACD, or DTS-CD into my computer and get MP3's out of it?

  • Audiophiles.. (Score:2, Interesting)

    by Flamekebab ( 873945 )
    I only speak for myself, but I know that I consider it silly encoding anything above about 150kbps ABR Ogg Vorbis, because above that, I can't hear the difference. I've been used to listening to 128kbps CBR MP3s for so long that I can't tell the difference any more. Sure, they're crappy PC speakers, but why bother with anything better if I simply cannot tell the difference. A musical friend of mine tried to test this - he played me a song twice, at different bitrates - I couldn't hear any difference. Surel
    • Sure, they're crappy PC speakers, but why bother with anything better if I simply cannot tell the difference.

      That is fine for you. I would save lots of money, time, and effort if I was content with listening to low quality MP3s on crappy PC speakers.

      I however, do not use crappy PC speakers, and I can and have been able to tell the difference between a late 90s or newer studio recording that was encoded to MP3 on my stereo that a friend brought over, and my friend and roommate asked "How can you tell it
      • One day, when I have more cash, maybe then I will be able to afford to be a quality snob. I think I'd rather save my cash for a better graphics card or monitor, things I can tell the difference with. Sometimes I *can* tell the difference, but I don't appreciate it - I listen to the music, not the quality. I mean, I have some music that is at 32kbits (MP3), the quality isn't great but it doesn't bother me when I listen to it, because the music takes precedent in terms of where I'm listening.
    • I generally concur. Using oggenc at default quality, I can't hear the difference. Not on headphones from my portable player (iHP-140) and not on PC speakers.

      This is probably because I've damaged my hearing already. The way I carry on I'll be deaf by 40 ;-)

  • Since I do audio-encoding for a living, I put a dictionary/Cookbook of command-line encoding tools [oreillynet.com] online.

    Doing the shorter clips was the hardest part, though I know it applies to very few people, hopefully you'll find it useful.

  • Are there any formats that offer high compression without loss? At some point you'd definately end up trading storage-space for CPU+memory, but for the latter they're only used on an as-needed basis and as time goes on the CPU power to handle this will increase as well.

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