PDA

View Full Version : M4A encoding only with QuickTime?



MrVideo
10-17-2004, 01:51 PM
From what I can see in codec central, the only way to get M4A encoded audio files is by using Quicktime 6.3, or later. Is there any particular reason that a codec doesn't exist for dBpowerAMP?

The problem is that Quicktime 6.3 is not compatible with another app that I use, which will never be updated so that it will.

If MP4 files can be encoded, why not M4A?

Please educate me on this.

ChristinaS
10-17-2004, 02:17 PM
Not sure about this but from the FAQ it looks to me like you can encode to MP4 with one of the other MP4 encoders and then rename the file so that the extension is M4A. I can't test this so I may be way, way off.

MrVideo
10-17-2004, 03:48 PM
Not sure about this but from the FAQ it looks to me like you can encode to MP4 with one of the other MP4 encoders and then rename the file so that the extension is M4A. I can't test this so I may be way, way off.

Maybe I don't quite understand the wrappers. In the MPEG-2 world, there are MPEG-2 program streams (containing both audio and video) and MPEG-2 video and audio streams, each containing only video or audio. I understand that MP4 is a program stream, containing both video and audio, and that M4A is an audio only stream. Even if MP4 doesn't contain any video, the MP4 wrapper is such that it can and as such can cause a problem with programs that only want M4A streams. So, just renaming MP4 to M4A won't solve the problem, unless I am full of it.

ChristinaS
10-17-2004, 04:03 PM
Maybe I don't quite understand the wrappers. In the MPEG-2 world, there are MPEG-2 program streams (containing both audio and video) and MPEG-2 video and audio streams, each containing only video or audio. I understand that MP4 is a program stream, containing both video and audio, and that M4A is an audio only stream. Even if MP4 doesn't contain any video, the MP4 wrapper is such that it can and as such can cause a problem with programs that only want M4A streams. So, just renaming MP4 to M4A won't solve the problem, unless I am full of it.
Hmmm, you may be right. But in your place I'd simply do a test and see what's happening. The worst that can happen is it won't work. I have no player that requires M4A files so I can't test this in any case.

Anyway, maybe this post will mean something to you: http://forum.dbpoweramp.com/showthread.php?t=4117

MrVideo
10-17-2004, 04:16 PM
Anyway, maybe this post will mean something to you: http://forum.dbpoweramp.com/showthread.php?t=4117

Thanks, I saw that posting. That is what confused me even more about the MP4/M4V/M4A wrappers.

hans-j�rgen
10-18-2004, 02:42 AM
I understand that MP4 is a program stream, containing both video and audio, and that M4A is an audio only stream. Even if MP4 doesn't contain any video, the MP4 wrapper is such that it can and as such can cause a problem with programs that only want M4A streams. So, just renaming MP4 to M4A won't solve the problem, unless I am full of it.
MP4 is the official file extension for the MPEG-4 container format, and it's allowed to have only one audio (or video or image etc.) track in a MP4 file, so simply renaming them is OK. M4A has been "invented" by Apple, just as M4B for bookmarkable M4As and M4P for protected M4As. See also the Wiki on Audiocoding.com for more:

http://www.audiocoding.com/modules/wiki/?page=MP4

Concerning your problem it seems that dBpowerAMP cannot use the different possible file extensions for AAC/MP4 due to an outdated implementation of mp4creator and/or PsyTEL AAC codecs. I guess Spoon will update that whole AAC/MP4 part when he has the time. For example the FAAC codec can produce .aac, .mp4, .m4a and .m4b files on its own, but the implementation in dBpowerAMP does not offer these options in the GUI.

MrVideo
10-18-2004, 01:17 PM
MP4 is the official file extension for the MPEG-4 container format, and it's allowed to have only one audio (or video or image etc.) track in a MP4 file, so simply renaming them is OK. [...] For example the FAAC codec can produce .aac, .mp4, .m4a and .m4b files on its own, but the implementation in dBpowerAMP does not offer these options in the GUI.

Thanks for the info. Do you know if dBpowerAMP is ever going to offer all of the available FAAC options?

hans-j�rgen
10-18-2004, 01:31 PM
No, that's a question that only Spoon can answer... ;)

Spoon
10-18-2004, 03:29 PM
To write .m4a file just edit the 'options.txt' file in the \Compression\FAAC

folder.