[gstreamer-bugs] [Bug 603695] New: Innaccurate seeking in MP3 files results in cut off playback

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=603695
  GStreamer | gst-plugins-ugly | 0.10.12

           Summary: Innaccurate seeking in MP3 files results in cut off
                    playback
    Classification: Desktop
           Product: GStreamer
           Version: 0.10.12
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-ugly
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: michael at mihu.de
         QAContact: gstreamer-bugs at lists.sourceforge.net
      GNOME target: ---
     GNOME version: ---


Summary:
I have the problem that seeking in MP3 files is not reliable, which results in
playback getting cut at the end of a file. 

How I discovered the problem:
I have some radio dramas as MP3 files.  Each episode is about 20 minutes long.
I used Totem on my Ubuntu 9.10 installation for my tests. When I start to play
one of these episodes and let it run until the end, everything is fine, the
playback is exactly as long as I expect it. But when I start to playback and
then seek to the middle and then let it play until the end, I noticed that a
few seconds are cut off at the end of the playback.

How I tried to create an artifical test:
In order to further analyse this, I recorded an audio file where I count from 0
to 59. Then I used an audio editor to exactly align the spoken words to the
exact second they represent. Next I encoded it to MP3 and did the test again
with this artifical data.

Outcome of test:
I noticed that when seeking in Totem, the playback can be off by 4 seconds.
That means, the display in totem is at 47 seconds, but from the loudspeaker you
hear the spoken "43". With my 20 minute testfile, the seeking is more off
towards the end of the file. Just try to seek to around 18 minutes.
Now when you let the file play until the end, Totem will stop the playback when
the 20 minutes are reached. But the playback is only at 19:56, which means that
the last 4 seconds of the playback are cut off.

Other tests:
When I encode the audio file to OGG or WAV, then seeking is accurate and the
playback won't be cut at the end. I tried different bitrates for MP3 and CBR
and VBR as well, but the problem remains. 

Wrap-up:
I think there is a bug with regard to seeking in MP3 files somewhere. 

Test files:
I put the test file on my web page, because it's too big for an attachment. The
MP3 is 20 minutes long and the size is about 15Mb. You can download it here:
http://www.mihu.de//mrec_vbr_192max.mp3

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