VideoHelp Forum
+ Reply to Thread
Results 1 to 8 of 8
Thread
  1. Member
    Join Date: Mar 2014
    Location: US
    Search Comp PM
    I have a bunch of AAC files I need to convert so they'll play on my car stereo.

    AAC, WAV, MP3, & WMA are the formats it is supposed to play, however, it seems to only recognize M4A format, and not AAC.

    I converted all the AACs to M4A, but I noticed very high sample rates (some nearing 1000 kb/s) along with significantly larger file sizes compared to the AAC originals.

    Researching here, it seems AAC and M4A are in fact different formats that cannot be "re-packaged"

    My goal being high sound-quality, what format/conversion method is recommended?

    Are the high sample rates inevitable with any kind of recoding? Strangely enough, a few random AACs (~192 kb/s) converted to M4A with slightly lower sample rates (~150 kb/s).
    Quote Quote  
  2. Member ozok's Avatar
    Join Date: Oct 2011
    Location: Turkey
    Search Comp PM
    Perhaps you can achieve what you want without re-encoding your files at all. It's best to avoid re-encoding when possible.

    You may first want to rename your files. AFAIK m4a is just a made up extension to distinguish audio only mp4 files. If renaming file extensions doesn't work, you may try muxing aac files into mp4 using yamb or such.
    Quote Quote  
  3. A Member since June, 2004 Keyser's Avatar
    Join Date: Feb 2013
    Location: Europe's westernmost point
    Search Comp PM
    By sample rate I guess you mean bitrate. Sample rate is a completely different thing. As for the file size, you are probably converting to ALAC (Apple Lossless Audio Codec).
    "The greatest trick the Devil ever pulled was convincing the world he didn't exist."
    Quote Quote  
  4. Member ozok's Avatar
    Join Date: Oct 2011
    Location: Turkey
    Search Comp PM
    Originally Posted by hogger129 View Post
    AAC is M4A.
    Not always. A file with aac extension can be a raw audio stream.
    Quote Quote  
  5. Member PuzZLeR's Avatar
    Join Date: Oct 2006
    Location: Toronto Canada
    Search Comp PM
    Ozok is right on. Try renaming files first. If that doesn't work, you can use Yamb or mp4muxer, which are both GUIs for mp4box and mp4creator respectively. This step is simply muxing, the "re-packaged" version you mentioned, by placing the audio stream into a different container, or simply demuxing it to a raw AAC stream - whatever works.

    If you're a newbie, and this is too much for you, just use a simple MP3 encoder, encode at constant bitrate, and 192kb/s to get most quality and you're done. BUT, I only say this if you keep the Source. I'm only suggesting an easy way to make it work in your vehicle, but it will lose quality and you SHOULD keep the Source separately if you do this.
    I hate VHS. I always did.
    Quote Quote  
  6. Member
    Join Date: Mar 2014
    Location: US
    Search Comp PM
    Originally Posted by ozok View Post
    Perhaps you can achieve what you want without re-encoding your files at all. It's best to avoid re-encoding when possible.

    You may first want to rename your files. AFAIK m4a is just a made up extension to distinguish audio only mp4 files. If renaming file extensions doesn't work, you may try muxing aac files into mp4 using yamb or such.
    Thanks, re-naming worked (I would have tried before asking here, but research led me to believe it wasn't even an option).

    Originally Posted by PuzZLeR View Post
    Ozok is right on. Try renaming files first. If that doesn't work, you can use Yamb or mp4muxer, which are both GUIs for mp4box and mp4creator respectively. This step is simply muxing, the "re-packaged" version you mentioned, by placing the audio stream into a different container, or simply demuxing it to a raw AAC stream - whatever works.

    If you're a newbie, and this is too much for you, just use a simple MP3 encoder, encode at constant bitrate, and 192kb/s to get most quality and you're done. BUT, I only say this if you keep the Source. I'm only suggesting an easy way to make it work in your vehicle, but it will lose quality and you SHOULD keep the Source separately if you do this.
    I appreciate the confirmation and your suggestion.

    Originally Posted by Keyser View Post
    By sample rate I guess you mean bitrate. Sample rate is a completely different thing. As for the file size, you are probably converting to ALAC (Apple Lossless Audio Codec).
    Yes, you're obviously right about my misnomer - and the format I had selected in DBPoweramp was Apple Lossless, with an m4a icon next to it (?).
    Quote Quote  
  7. Member
    Join Date: Nov 2013
    Location: Serbia
    Search Comp PM
    Yes, M4A is MP4 contaner format extention for audio-only files. MP4/M4A can store ALAC (Apple Lossless Audio Codec) or AAC (Advanced Audio Coding), which is lossy codec. In both cases extention is same - M4A.
    Quote Quote  



Similar Threads