When converting to cbr format, the file shows as vbr (version 2.1.4 )

Asked by chuck-dtol on 2014-10-09

I've found that karaoke files (mp3+cdg) have problems playing as vbr under some systems, so I always used SoundConverter to make the VBR mp3s into CBR mp3s.

I just noticed that a behaviour has changed (perhaps in the last ubuntu 14.04 update (SoundConverter 2.1.4)). When converting mp3 files to 128kbps CBR format mp3s, mp3tag shows the files as VBR (with the correct 128k bitrate). VLC shows them as 48Kbps (but does not indicate CBR or VBR). Perhaps it is a library change (such as gstreamer or lame), but I'm not sure what to look for.

Anyone else seen this happen and can advise how to get SoundConverter to output files set to CBR again? With hundreds of files to convert, I don't want to mess them up or cause a future problem.

Question information

Language:
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Status:
Answered
For:
Ubuntu soundconverter Edit question
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Last query:
2014-12-03
Last reply:
2014-12-04
Launchpad Janitor (janitor) said : #1

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

GautierPortet (kassoulet) said : #2

The generated CBR files are indeed detected as VBR. They seem to only have only one bitrate, the same for each frames.
The parameters for the mp3 encoder are right, so there is something strange happening.

The playback should be ok, I've now to test if gstreamer 1.0 have the same behaviour.

chuck-dtol (chuck-colford) said : #3

Thanks for confirming you see the same behaviour. Indeed it is strange.

GautierPortet (kassoulet) said : #4

Removing the xingheader doesn't solve the problem.

This is the error I get with mp3check :
frame 1/ 0:00: bitrate switching (48 -> 128)

The problem is still here in gstreamer 1.2.4, and the code seems right.

http://cgit.freedesktop.org/gstreamer/gst-plugins-ugly/tree/ext/lame/gstlamemp3enc.c#n883

All frames are in the selected bitrate appart from the first.

GautierPortet (kassoulet) said : #5

My bad, removing the xingheader *does* solve the problem.

This is now fixed !

chuck-dtol (chuck-colford) said : #6

Gautier: Merci beaucoup! Thanks for looking into this and finding the root cause. Can I fix it on my end or do I just watch Github for the code change?

Again - Tres bien merci!

chuck-dtol (chuck-colford) said : #7

I see the code I think you are talking about (line 651-653 in gstreamer.py. I can try commenting it out and see if the CBR mp3 is now detected as CBR.

Can you help with this problem?

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