FS#10470 - Vorbis decoder glitches
Opened by Christopher Williams (christop) - Tuesday, 28 July 2009, 04:02 GMT
Last edited by Andree Buschmann (Buschel) - Thursday, 03 February 2011, 19:59 GMT
While playing Michael Jackson's "Beat It" encoded as Ogg Vorbis (quality 2.0), I noticed some subtle clicks in the left channel at some points in the song. I played around with all sorts of audio settings (volume, bass, treble, crossfeed, etc) to try to get rid of it, but it still exists with all of those. Then I enabled the equalizer and changed the Precut to -3.0dB. This got rid of the clicks.
I recorded the left channel output of my Sansa to my computer at 96k sample rate with different levels of Equalizer Precut. All of the audio settings besides Precut are set to 0 or are disabled. I attached a screenshot of the waveform, and I highlighted the waveform of one "click" to make it glaringly obvious. The -2.0dB and -3.0dB recordings look fairly close to the original ogg, with a bit of smoothing.
I also attached a 10-second sample of the song (encoded in ogg vorbis, quality 2.0) which triggers this glitch for me. The click is at about 8.1 seconds into the sample. This happens in the "S" sound in the words "So beat it" (only in the left channel).
It should be noted that I also played an mp3 and a WAV (or Wavpack) encoded version of the same song, also on my Sansa, and I couldn't hear any clicks in them. I also played the Ogg file on my computer and couldn't hear any clicks there either. I also tried different encoding qualities, and at lower qualities (-1.0) the clicking was worse. I haven't tried higher qualities. I can record those samples as well if someone is interested.
From what I can tell, there is probably some numeric overflow in the vorbis decoder. I haven't had much chance lately to look at the code to say for sure, though.
Thursday, 03 February 2011, 19:59 GMT
Reason for closing: Out of Date
Additional comments about closing: Outdated, no feedback since 9 months. No file available for further investigation.