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Subject: Re: Sandisk Sansa Clip+ certain MP3 won't playback

Re: Sandisk Sansa Clip+ certain MP3 won't playback

From: R.L. Horn <lists_at_eastcheap.org>
Date: Sat, 29 Jan 2011 22:39:04 -0600 (CST)

On Sat, 29 Jan 2011, Magnus Holmgren wrote:

> On 2011-01-28 19:18, Boomer wrote:
>
>> Some mp3s won't parse correctly, according to the simulator, so they
>> won't play or show up in the database.

> One common reason for MP3:s not playing is that the CRC field in each frame
> is incorrect, but it doesn't look like that is the case here (it wouldn't
> prevent the file from showing up in the database). Hard to say what the
> problem is without having a file to test with.

Usually, when I run across something that won't play (which is to say
isn't recognized), it comes down to a bad ID3 tag or other extraneous
junk.

In particular, there's something relatively popular out there that doesn't
know how to compute tag lengths (it uses the length of the entire tag, not
the tag minus the first ten or twenty bytes). Here's an example:

   0000000: 4944 3303 0000 0000 003a 434f 4d4d 0000 ID3......:COMM..
   0000010: 0026 0000 0000 0000 0072 6566 6572 656e .&.......referen
   0000020: 6365 206c 6962 464c 4143 2031 2e31 2e34 ce libFLAC 1.1.4
   0000030: 2032 3030 3730 3231 3300 fffb 9264 0000 20070213....d..

The tag length (starting at byte 6) *should* be 0x00000030, not 0x0000003a
and, as a result, Rockbox (along with other strict ID3-aware players)
completely misses the first mp3 frame at byte 0x3a.

I don't know if this is the OP's issue or not, but these files do produce
the symptoms he described so far as skipping playback is concerned. I
don't use the database, so I can't comment on any problems there.
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Received on 2011-01-30


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