MP3 - M4a large files

[Unregistered]

I'm trying to convert a large MP3 file (20 hours or more) to M4a. It converts only part of it, like 8 hours, and the last half hour is corrupted. When I try to use iTunes to convert it, it converts only 7 hours. The mp3 works just fine. Am I doing something wrong?

[Spoon]

Re: MP3 - M4a large files

How large is the m4a file (in bytes)?

[hans-j�rgen]

Re: MP3 - M4a large files

Which AAC codec do you use, and what is the file size of the AAC file?

[Unregistered]

Re: MP3 - M4a large files

I started out with a 85,543mb mp3 file. The one I create with iTunes is 164,174mb. The one I create with dbpa with the mp4 (cli) codec is 202,884mb.

[ChristinaS]

Re: MP3 - M4a large files

Ok, I'm just going to be ranting for a while here, as it's all speculation on my part. I cannot even begin to imagine a 20 hours mp3 file!

I think you're hitting an internal space limit. I think the conversion involves converting first to wav internally and then to whatever else. When it goes to wav, it's probably limited by whatever space you have available.

Do you mean your mp3 file is over 80 giga-bytes???? Even a wav file for 20 hours would be about 13GB (assuming 16-bit 2-channel stereo PCM wav which is about 11MB/minute and 1200 minutes)

Could it be about 850 MB instead? That would be about 42MB for 1 hour, thus about 700KB per minute - so maybe it's encoded at around 96kbps?


Because if it is 8500 MB that's over 8GB and it would mean it's encoded at 960kbps? And at 85000 MB (over 80GB) it's way larger than a cd quality wav and it would be encoded at 9600KBPS? Never heard of such encoding bitrates! (or are my calculations all off by a factor of 10 or 100 ????)

So, assuming it is 850MB this would decode to a wav about 11MB*1200 min = 13200MB or 13GB. Maybe it cannot find 13GB to work with (or maybe it's got an internal limit that's lower than that), but it may stop somewhere around 4GB from further processing, which would give you 7 or 8 hours, or about a third.

Actually my initial thought was that it would work in ram, but obviously this is not the case if you got this far.

[Unregistered]

Re: MP3 - M4a large files

oops. yeah, i meant to write kb. forgive me, i just got back from 3 hours of calculus, my mind is overwhelmed by numbers.

i hadn't thought about it converting it to wav first. is that what dbpa does? i will try it on a larger harddrive. thanks =]

[ChristinaS]

Re: MP3 - M4a large files

oops. yeah, i meant to write kb. forgive me, i just got back from 3 hours of calculus, my mind is overwhelmed by numbers.

i hadn't thought about it converting it to wav first. is that what dbpa does? i will try it on a larger harddrive. thanks =]

But then it would be 20 hours for an 85MB mp3 file. Is it at an excruciatingly low bit rate like 8kbps? mono? low frequency? In any case, I think it goes first through a wav (but maybe not quite cd quality 44.1KHz, stereo, something less hi-fi) and then it gets converted to whatever you asked. So the wav has got to fit somewhere in the meanwhile.

The absolute smallest wav file I can see dMC can create is 8-bits, mono, 8000Hz or compressed PCM at 7kbps, 8000Hz, mono. This is about 460KB/minute so your 20 hours would be about 540MB. Then if it stopped at around 7-8 hours, i.e. 1/3 of the way through, that means it created a wav of about 180MB - so it could have been done in ram and maybe that's all you had available. Maybe the hard disk doesn't quite come into play yet.

Again, this is just speculation on my part and playing with numbers as I perceive them.

[Unregistered]

Re: MP3 - M4a large files

This particular MP3 was only 8 hours long, not the 20 hour one I spoke of earlier. I chose a smaller one to convert after the twenty hour one. It still only converted about 7 hours. The mp3 is at 24kpbs mono.

[Unregistered]

Re: MP3 - M4a large files

I created the m4a file on another computer and it stopped at exactly the same point. I guess there must be something wrong with the mp3 file that keeps it from decoding/encoding but doesn't affect playback.

[hans-j�rgen]

Re: MP3 - M4a large files

OK, what is the mp4 (cli) codec in dbpowerAMP, PsyTEL plus mp4creator or FAAC (maybe Spoon or any of the regulars could answer that)? Anyhow, if it's PsyTEL, dbpowerAMP always has to decode the input file to WAV first, because that AAC codec doesn't support piping to stdin which would avoid huge temporary WAV files. I don't know if the FAAC implementation in dbpowerAMP uses its stdin (which would make sense) or if it works with temporary WAV files, too, but not enough free HDD space or a 2 GB internal file size limit might be a reason for this error then (AACmachine was developed because of that PsyTEL flaw back then).

Another test you might try is to convert to the .aac file format first, not .m4a, because that would eliminate any possible problems with the MP4 file muxer.

There are other transcoders that might work with your large MP3 file, e.g. foobar2000, Speek's Multi frontend or GX::Transcoder. By the way, you seem to use wrong settings, because the M4A file is bigger than the MP3, and probably you want to reduce the bitrate/file size, right? On the other hand 24 kbps/mono shouldn't be reduced any further in my opinion...

Are you trying to convert audio books from MP3 to M4A or rather M4B to play them on your iPod maybe? Then another workaround would be to cut the MP3 into smaller parts with a tool like mp3directcut first and then encode them to M4A/M4B.

[Unregistered]

Re: MP3 - M4a large files

Yes, I am trying to convert audiobooks. So I tried splitting the tracks, but it had 617 sync errors. I guess that answers my question about it being a good MP3 or not... Is there any way I can get around this? It wouldn't even create the last split. Would those other programs you spoke of be able to do anything different?

[hans-j�rgen]

Re: MP3 - M4a large files

If you listen through these long MP3 files, are there any glitches or obvious errors in them? You could try to transcode them in foobar2000, because it definitely uses piping (= no temporary WAV) while GX::Transcoder also produces large WAVs in between. So if your MP3 files play without errors in foobar2000, they should also transcode to M4A/M4B without problems.

You'll need the command line version of FAAC, too, if you want to encode directly to M4B files. If you simply encode to M4A, using the foobar 2000 special installer with the included foo_faac.dll plugin is enough. You can always rename them to bookmarkable M4B files afterwards.