Problem with IMA ADPCM decoding

[Tiago Katcipis]

Sebastian,

Opened a bug for this:

https://bugzilla.gnome.org/show_bug.cgi?id=727975

On this week i will take a closer look at it.




On Wed, Apr 9, 2014 at 2:25 PM, Tiago Katcipis <katcipis at inf.ufsc.br> wrote:

> Hi,
>
> I'm having some funny issues while trying to decode IMA ADPCM files. I'm
> working with mono/8000hz IMA ADPCM WAV files and when i try to play then
> with gst-launch i can hear a lot of audio gaps on the audio, and the
> total playback time is at half of the original audio file.
>
> If i play the audio with "play", it plays correctly.
>
> Debugging a little further, it seems that someone on the pipeline (my bet
> is on adpcmdec) is generating holes on the stream that causes the audio
> to be all messed up. If i use a audioparse to correct the holes, the
> audio plays correctly.
>
> To generate a audio file on the IMA ADPCM format that causes the problem:
>
> gst-launch-1.0 audiotestsrc num-buffers=10 samplesperbuffer=8000 !
> audio/x-raw,rate=8000,format=S16LE ! wavenc ! filesink location=test.wav
>
> sox test.wav -e ima-adpcm test-adpcm.wav
>
> Perfect playback (~10 seconds of audio):
>
> play test-adpcm.wav
>
> Messed up playback (~5 seconds of audio):
>
> gst-launch-1.0 filesrc location=test-adpcm.wav ! wavparse ! adpcmdec !
> audioconvert ! pulsesink
>
> Perfect playback (~10 seconds of audio):
>
> gst-launch-1.0 filesrc location=test-adpcm.wav ! wavparse ! adpcmdec !
> audioparse channels=1 rate=8000 raw-format=4 ! audioconvert ! pulsesink
>
> It seems that half of the audio is lost on this gap problem, but the audio
> is there since with audioparse everything goes just fine.
>
> audioparse did not completely resolved my problem, because i need to
> query the duration of the audio in time, and doing this with this pipeline
> returns half the real duration of the audio, even with audioparse (makes
> sense with the rest of the problems i found).
>
> I will continue to investigate the problem, just wanted to now if this is
> a know problem or if I'm doing something wrong. If it is really a problem i
> can open a bug.
>
> The tests have been executed on a Ubuntu 12.04 with Gstreamer 1.2.1.
>
> Best Regards,
> Tiago Katcipis
>
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