M4A Files

[Mike W]

Hi, I have a number of M4A files on the Brennan but unfortunately they won't play.

If I try and play them, the B2 shows the track on the now playing screen and then after a couple of seconds moves on to the next track.

I have run scan disk, the B2 sees the tracks ok.

If I access the B2 via my pc and log into the B2 I can select the M4A file and it will play no problem on my windows music player.

Anyone any ideas?

Thanks

Mike

[Daniel Taylor]

 I'm not sure, but although the B2 can only be set to rip MP3s at two different bit rates, it's supposed to be able to play at any rate it encounters when you import the files already ripped somewhere else.  All that said, I wonder if you have tracks ripped at a bit rate it won't handle.  I read somewhere the other day about a machine that would not play variable bit rate MP3 files.

For a test, if you are able, re-rip one of the songs that will not play.  Rip it at one of the B2's preferred bit rates.  Give it the identical filename.  Then replace the previous file with the new one and see if it will play.

[Daniel Taylor]

Aaaarrrgh!  You said M4A files, and I started talking about MP3 files.  I don't know if M4A files can be a different bit rates or not.  But if so, maybe my thoughts might still be valid.

[Mike W]

.

Thanks Daniel, I uploaded these files to the B2. Not sure where I got them from but they played on my pc and my phone.

Not sure about bitrates etc other than the B2 sees the files but will not play them.

I searched the forum and it seems that the M4a format should play.

Regards

Mike

[Daniel Taylor]

In the total stats, does the B2 count them as AAC files?

The fact that the B2 sees the file and lets you select it, but then stops attempting to play it suggests that there is something about the file that is causing trouble for the B2.

I'm I correct to recall that M4a and AAC files are lossless?  Either way, they can be converted to another format.  That might be worth a try.  Of course, you'll have to do it on your PC - the B2 can't do that.

[lesliebr...@gmail.com]

Hi Mike, some info that might help from Google.

AAC and MP3 are both lossy audio compression formats. AAC is the default format used by iTunes. It produces better audio quality than MP3 for a given data rate (e.g., 128 kbps) and is playable in almost all software that can play MP3 files.

There are raw video and audio streams, these streams cannot be played directly on most video/audio player, they need to be "encapsulated" on a transport, a raw H.264 video stream and a raw AAC audio stream need to be inside a MP4 encapsulator, it can be also inside an AVI or MOV encapsulator.

A MP4 file can contain a H.264 video stream and/or an AAC audio stream, but for some reason someone decided that a MP4 file that contains video and audio use the file extension M4V (v for video) and if it is an MP4 file that only contains audio to use the M4A extension, that is a common practice in other encapsulators like Windows Media which use WMV and WMA, or OGG which use OGV and OGA, silly as it seems.

So a file that has a M4A file extension is an MP4 file that can contain a AAC audio track but it is not always the case, that's why programs like mediainfo become handy to know what is inside a file.

Seems there can be more than just audio in an M4A. Might be worth checking out mediainfo. 

MediaInfo is a free, cross-platform and open-source program that displays technical information about media files, as well as tag information for many audio and video files. It is used in many programs such as XMedia Recode, MediaCoder, eMule, and K-Lite Codec Pack.

Have never used mediainfo, just came across it in google answers. Might be useful.

[Mike W]

Thanks for the information Leslie, I've tried Mediainfo, see screenshot below. It seems to be saying that its a standard M4A audio file and should play but just will not do so on the B2.

I've bitten the bullet and converted all of the tracks to mp3 and they now play ok.

Not sure what the underlying problem is but at least I can play the track.

Best regards

Mike

[lesliebr...@gmail.com]

Hi Mike, noticed the bitrate is shown as 126 kbps, and the normal bitrate is 128 kbps for AAC and low-end mp3s. Wonder, is that the problem? At least you can play them now. Might be worth checking any other M4A files you have that do play with mediainfo, to compare their bitrates.

[PMB]

Hi Mike,

I downloaded some ALAC files which have an m4a extension and found these play OK on the B2. It does list these as AAC files when you open the stat's.

Paul
Brennan Support.

[lesliebr...@gmail.com]

Hi Paul, in Mike's screenshot the bitrate shows as 126 kbps. Normally, bitrates are multiples of 64 ie. 64 kbps, 128 kbps, 192 kbps, 256 kbps and 320 kbps. Would th e rate being 126 kbps prevent the tracks playing? 

[PMB]

Hi Leslie,

Well spotted. Not something I can answer so will forward to Martin.

A quick Google search does suggest that typical bit rates for AAC are 128k, 192k and 256k, so it might be the issue.

Digging a bit deeper Mike's files are 'AAC LC' which appears to be optimised for streaming audio with less data. Possibly the B2 doesn't recognise 'LC' version of AAC.

Paul
Brennan Support.

[lesliebr...@gmail.com]

Well spotted you too, Paul. I didn't notice the "AAC LC" bit.  

Mike, you said you had a number of M4A files that won't play. Curious what the bitrates are for them. Are they also showing as AAC LC and 126 kbps?

[Mike W]

I've just checked the others and they are all the same bitrates, 126.

These came from my wife's Itune library, I don't think there was any processing done to them. They play on other audio players fine I didn't forsee a problem with them on the B2.

They do appear on the status page as AAC files.

Having converted them to mp3, which went smoothly, they now play fine on the B2.

Regards

Mike

[PMB]

Hi Mike,

Thanks for the update. Glad you have found a work around.

Great album - Out of the Blue....

Paul
Brennan Support.

[Mike W]

Hi Paul, I agree. Went to see the ELO Experience a couple of weeks ago, really great music extremely true to the original.

This is what prompted me to want to play them on the B2 which is when I encountered the problem, all up and blasting away now though!

Regards

Mike