Rockbox

  • Status Closed
  • Percent Complete
    100%
  • Task Type Bugs
  • Category Music playback
  • Assigned To No-one
  • Operating System iPod Nano
  • Severity Low
  • Priority Very Low
  • Reported Version
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by Didro - 2007-03-30

FS#6942 - Bug with bitrate determination

I have MP3 file which is 2 hour long and has bps = 192, but rockbox player determinates that bps = 24 (which is 192/8) and lenght = 16 hour (2*8). Apple’s firmware and Winamp show information about this file correctly.

Closed by  amiconn
2007-04-17 18:04
Reason for closing:  Not a Bug
Additional comments about closing:   Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407

Rockbox relies on the Xing VBR header if the file is VBR. If it isn\'t present it assumes CBR and does its playtime calculation based on the bitrate of the first frame. PC based media players can check the whole file to determine the correct bitrate, rockbox doesn\'t do this in order to save battery. Adding a proper Xing header to the file will fix the display in rockbox. One option is to use the vbrfix plugin, as you did.

Project Manager
linusnielsen commented on 2007-03-30 11:34

I would like to have the file for analysis, else I can't find out what is wrong.

Didro commented on 2007-03-30 12:05
I would like to have the file for analysis, else I can't find out what is wrong.
It has 180 MB, so its unreal to upload it for me. It is interesting for me where does rockbox player take information about length of file?
Project Manager
linusnielsen commented on 2007-03-30 12:25

The bitrate and the length is taken from the MP3 frame headers, and/or the Xing/LAME header. In fact, it is only important to have te first megabyte of the file, if you are able to cut it out for me. Don't cut it with an audio editor, but with a hex editor or similar, for example the 'dd' tool.

Didro commented on 2007-03-30 13:02

OK, I'll try. I think maybe in MP3 header of this file is invalid information, but Apple's firmware and different windows programms can determine bps and length in some other way. I'll also test this file by different Mp3 readers.

Didro commented on 2007-03-30 14:46

I've open this mp3 with VBRfix, now it shows me lenght: 1 min 10 sec, bps: 19646 :-)))

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