Workaround for broken(?) m4a files from ffmpeg, was Re: [PATCH] Output AAC as M4A for iTunes with metadata tags

[Simon Nash]

Simon Nash wrote:
> richard wrote:
>> On Mon Apr 11 12:24 Simon Nash wrote:
>>
>>> In the DecoderConfigDescriptor within the esds atom, there's
>>> a field named avgBitrate (average bit rate).  In the file that doesn't
>>> play, this field is set to zero.  In the file that does play, this 
>>> field is set to a non-zero value.
>>
>> That ties in with what EasyTag was reporting. It gave an incorrect
>> bitrate. I referred to it earlier. See last paragraph here:
>>
>> http://lists.infradead.org/pipermail/get_iplayer/2011-March/001129.html
>>
>>> I have sent Richard a .mp4 file created in this way for him to try.
>>
>> That won't play in the Marantz as its a video file. I need a m4a file to
>> test.
>>
>>
>>
> I'm puzzled by this.  There is definitely no video in this file, and
> it plays OK on my Linn DS.  The Linn DS is happy with both .mp4 and .m4a
> file extensions so I had been thinking that these are equivalent for
> MPEG-4 files with audio and no video.  Have you tried renaming the file
> to test1.m4a?  I tried recreating it as a .m4a file using mp4creator but
> the results were identical except for some timestamps.
> 
After thinking about this some more, I noticed that mp4creator produces
files with the ftyp atom set to mp42, even when the output file extension
is .m4a.  I sent Richard a patched file with ftyp set to M4A for him to try.

   Simon

>   Simon
> 
> 
> 
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