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Determining the bitrate of caf files

post #1 of 12
Thread Starter 

I have some caf files.

 

How can I determine the bitrate?

post #2 of 12
Quote:
Originally Posted by superdragon View Post
 

I have some caf files.

 

How can I determine the bitrate?

 

sox --i yourfile.caf

 

will probably work. Can you upload it somewhere?

post #3 of 12
Thread Starter 

I'm assuming that sox is some kind of Linux command or Linux program.  I'm on Windows.  I'd prefer not to upload the files anywhere as I purchased them.

 

I bought Aieeesoft audio converter and converted 2 caf files to ALAC m4a files.

 

One of the converted m4a  files is listed as 550 kbps and the other as 720 kbps.  I'm assuming the converted files match the bitrate of the originals. Can you verify this?

 

I was asking for a reason.

 

I've been playing around with some brainwave entertainment files from http://www.unexplainablestore.com/  They sell downloadable mp3 files on their site which are 320 kbs.  They also have an iPhone app (99 cents) that offers in app purchase of the exact files files for much cheaper prices, such as 1/3 of the price of the download version.  I wanted to know whether the quality is the same.

 

As my iPhone is jailbroken, I was able to copy the files (downloaded to the iPhone as caf files) to my PC to look at them.

 

Some other stats:

 

Caf file #1 45 minutes 120 meg - converted to ALAC m4a - 177 Meg

 

Caf file #2 -5:02 13.5 MEG - Converted to m4a 25.9 Meg

 

Also, for fun - I made a compressed rar file fo the larger m4a but it compressed 0%.  The source caf compressed around 30%

 

I am not an audiophile by any means, but from the information that you provided, is it clear that the cheaper audio files that I purchased on my iPhone are the same quality, if not better, than the quality that they offer to download?  If it helps for the answer, a 10 minute 320 kbbs mp3 that I purchased from the site is 22.8 Meg.

 

Thanks

post #4 of 12
Quote:
Originally Posted by superdragon View Post
 

I'm assuming that sox is some kind of Linux command or Linux program.  I'm on Windows.  I'd prefer not to upload the files anywhere as I purchased them.

 

I bought Aieeesoft audio converter and converted 2 caf files to ALAC m4a files.

 

One of the converted m4a  files is listed as 550 kbps and the other as 720 kbps.  I'm assuming the converted files match the bitrate of the originals. Can you verify this?

 

I was asking for a reason.

 

I've been playing around with some brainwave entertainment files from http://www.unexplainablestore.com/  They sell downloadable mp3 files on their site which are 320 kbs.  They also have an iPhone app (99 cents) that offers in app purchase of the exact files files for much cheaper prices, such as 1/3 of the price of the download version.  I wanted to know whether the quality is the same.

 

As my iPhone is jailbroken, I was able to copy the files (downloaded to the iPhone as caf files) to my PC to look at them.

 

Some other stats:

 

Caf file #1 45 minutes 120 meg - converted to ALAC m4a - 177 Meg

 

Caf file #2 -5:02 13.5 MEG - Converted to m4a 25.9 Meg

 

Also, for fun - I made a compressed rar file fo the larger m4a but it compressed 0%.  The source caf compressed around 30%

 

I am not an audiophile by any means, but from the information that you provided, is it clear that the cheaper audio files that I purchased on my iPhone are the same quality, if not better, than the quality that they offer to download?  If it helps for the answer, a 10 minute 320 kbbs mp3 that I purchased from the site is 22.8 Meg.

 

Thanks

 

120MB for 45mins would mean about 355kbps, which would jive with the quality being around what 320kbps mp3 would give you. You can always buy the two versions of the same file and compare them.

post #5 of 12
Thread Starter 
Quote:
Originally Posted by RRod View Post
 

 

120MB for 45mins would mean about 355kbps, which would jive with the quality being around what 320kbps mp3 would give you. You can always buy the two versions of the same file and compare them.

I might do that for fun.  What would I do to compare an mp3 with a caf?

 

Right clicking on an mp3 or an m4a, choosing properties, shows me the bitrate.  Is there some windows tool that will give me the same information for caff files?

post #6 of 12
Quote:
Originally Posted by superdragon View Post
 

I might do that for fun.  What would I do to compare an mp3 with a caf?

 

Right clicking on an mp3 or an m4a, choosing properties, shows me the bitrate.  Is there some windows tool that will give me the same information for caff files?

 

Note sure on Windows, sorry, though you can get SoX for windows. For comparison, you can convert both files to WAV and do all kinds of stuff. You could throw them into something like Audio DiffMaker to get a sense for the differences after accounting for things like average volume, for instance.

post #7 of 12
Thread Starter 
Quote:
Originally Posted by RRod View Post
 

 

Note sure on Windows, sorry, though you can get SoX for windows. For comparison, you can convert both files to WAV and do all kinds of stuff. You could throw them into something like Audio DiffMaker to get a sense for the differences after accounting for things like average volume, for instance.

Rrod,

 

This is a related question:  Can you please explain the math here:

 

The 177 Meg ALAC file that I converted is reported as 550 kbbs.  I used the same software to convert the source caf file to a lossless WAV.  The WAV is huge - 494 MEG.  I understand that ALAC is compressed and can verify this because the m4a does not get smaller after I make a RAR from it, but I can compress the WAV 45%.

 

Here is my question:  Why is the WAV reported as 1536 kbps?  Correct me if I am wrong, but the WAV and m4v should be the exact quality, assuming that the converter is doing its job.

post #8 of 12
Quote:
Originally Posted by superdragon View Post
 

Rrod,

 

This is a related question:  Can you please explain the math here:

 

The 177 Meg ALAC file that I converted is reported as 550 kbbs.  I used the same software to convert the source caf file to a lossless WAV.  The WAV is huge - 494 MEG.  I understand that ALAC is compressed and can verify this because the m4a does not get smaller after I make a RAR from it, but I can compress the WAV 45%.

 

Here is my question:  Why is the WAV reported as 1536 kbps?  Correct me if I am wrong, but the WAV and m4v should be the exact quality, assuming that the converter is doing its job.

 

1536 kbps is what you'd expect from a uncompressed 16/48 file. ALAC uses lossless compression (à la rar), so space is used more efficiently. FLAC does the same, though in a slightly different manner that manages to pack thing even a little bit better, on average.

As far as I know CAF is just a simple container for PCM audio, no compression, like AIFF and WAV. Why the size is increased when converting from CAF to ALAC I do not know.

Or maybe the CAF files you have are simply 'wrapped' AAC files. Could this be true?


Edited by limpidglitch - 3/22/15 at 4:17am
post #9 of 12
Quote:
Originally Posted by limpidglitch View Post
 

 

1536 kbps is what you'd expect from a uncompressed 16/48 file. ALAC uses lossless compression (à la rar), so space is used more efficiently. FLAC does the same, though in a slightly different manner that manages to pack thing even a little bit better, on average.

As far as I know CAF is just a simple container for PCM audio, no compression, like AIFF and WAV. Why the size is increased when converting from CAF to ALAC I do not know.

Or maybe the CAF files you have are simply 'wrapped' AAC files. Could this be true?

 

CAF can contain compressed files. Here's the list on the specifications site:

    kAudioFormatLinearPCM      = 'lpcm',
    kAudioFormatAppleIMA4      = 'ima4',
    kAudioFormatMPEG4AAC       = 'aac ',
    kAudioFormatMACE3          = 'MAC3',
    kAudioFormatMACE6          = 'MAC6',
    kAudioFormatULaw           = 'ulaw',
    kAudioFormatALaw           = 'alaw',
    kAudioFormatMPEGLayer1     = '.mp1',
    kAudioFormatMPEGLayer2     = '.mp2',
    kAudioFormatMPEGLayer3     = '.mp3',
    kAudioFormatAppleLossless  = 'alac'

post #10 of 12

Yeah, I noticed that. Or rather I checked the afconvert help file, which states:

'caff' = Apple CAF (.caf)
               data_formats: '.mp1' '.mp2' '.mp3' 'QDM2' 'QDMC' 'Qclp' 
                             'Qclq' 'aac ' 'aace' 'aach' 'aacl' 'aacp' 
                             'alac' 'alaw' 'dvi8' 'ilbc' 'ima4' I8 BEI16 
                             BEI24 BEI32 BEF32 BEF64 LEI16 LEI24 LEI32 
                             LEF32 LEF64 'ms\x00\x02' 'ms\x00\x11' 'ms\x001' 
                             'samr' 'ulaw'

 

I don't know if this little program is available for Windows, but it seems to do a good job at extracting the file, rather than re-encode it. Only trouble is that you need to know beforehand in what format the file you're trying to extract is, but soxi should give you that information.

post #11 of 12
Thread Starter 

Support staff for the mobile app got back to me.  The tell me that the files that hit the iPhone (caf) are the same 320 kbps quality as the downloadable mp3s.  They also acknowledged the pricing difference between the platforms, describing operating and marketing costs.  Still freaky that mobile downloads for the same files are as much as 1/3 of the cost of the downloadable mp3s.

post #12 of 12
Quote:
Originally Posted by superdragon View Post
 

Support staff for the mobile app got back to me.  The tell me that the files that hit the iPhone (caf) are the same 320 kbps quality as the downloadable mp3s.  They also acknowledged the pricing difference between the platforms, describing operating and marketing costs.  Still freaky that mobile downloads for the same files are as much as 1/3 of the cost of the downloadable mp3s.

 

Nothing surprises me in this business any more. Glad they got back to you on that. Did the mean that it's exactly the same MP3 just wrapped in a CAF container?

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