• Registered: 2007-07-23
  • Posts: 86

Topic: 0.08: Audio stuttering during skipping song

0.08 r879, audio output device: Aggregate audio device, made of Soundflower 2ch and of the builtin audio. The sound comes out of Cog, goes into Soundflower, it is taken by AU Lab from Apple, processed, and then outputted to the builtin audio.

Between the end of a song and the next one everything ok, also when jumping to a specific position of the track, but when I skip to the next song I hear the audio stuttering for a couple of seconds.

Is it related to the gapless playback?
I don't remember experiencing this problem with 0.07 under either Tiger or Leopard.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

It probably depends in LAconvolver, since disabling it in AU Lab makes the problem disappear. Cog simply exposed the bug.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

I noticed that it doesn't happen every time, the same track may cause it or not, depending on the number of seconds played. Should I send two example tracks for testing? at least to exclude Cogx as source of the problem?

  • Registered: 2007-07-08
  • Posts: 790

Re: 0.08: Audio stuttering during skipping song

How much CPU is in use (from Cog & AULab and all that)? I have noticed a few stuttering issues under high load that need to be taken care of.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

About 20% (out of 200% maximum), on an iMac Core 2 Duo 2,4 GHz.

  • Registered: 2007-07-08
  • Posts: 790

Re: 0.08: Audio stuttering during skipping song

I'll add this to trac and try out a similar setup.

Does it only occur for certain file types? You say it depends on the number of seconds played? Does that mean it happens when you seek at the end of the song, but not at the beginning?

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

It never happens for seeks within the same song (as far as I remember), it happens only while skipping to the next, previous or any other song (I tried only mp3s).

I found that it happens very often (almost always) if done within the first seconds since cog started to play (=skip within the song, skip to another song). With examples:
-skip to next -> few seconds played -> skip to next => stuttering
-skip to within the song -> few seconds played -> skip to next => stuttering
-play the same song as before, but 20 seconds -> skip to next -> no stuttering
If you tell me which tests you would like me to do, I will make them this evening.

Since Cog, as discussed in other threads, is gapless and feeds the audio device with a continuous stream, without interruptions (or so I understood), could the problem arise only with aggregate devices? my output device is made of soundflower (input) and the real iMac audio card (output). Or maybe it depends on cog+soundflower? (as far as it concerns Cog, my aggregate audio device is made only of soundflower 2ch, the other part of the aggregate device is used only by AU Lab).

  • Registered: 2007-07-08
  • Posts: 790

Re: 0.08: Audio stuttering during skipping song

I see now. Cog is only gapless when changing streams automatically. When you are changing tracks manually, that is not gapless, but it still shouldn't stutter. I'll take a look when I get a chance.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

Additional note: when I seek multiple times within the same same file in a short period of time (1 second between seeks), I get a "recoverable error" in the Console.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

Update: I found that my sound card was set to 44100 Hz/24 bit, while this iMac can up to 96k  Hz/24 bit. I set it to the maximum capabilities and now the problem seems solved.

The error message "recoverable error" in the console is still there.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

It seems it's only less frequent, I experienced it again :-/

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

Could the gapless feature be disabled? at least temporarily in current betas, until the problem of stuttering is fixed.

  • Registered: 2007-07-08
  • Posts: 790

Re: 0.08: Audio stuttering during skipping song

Disabling gapless wouldn't fix any stuttering issues. It's hard to say what's happening. Are the files on a network drive?

Recoverable error just means Cog hit an id3 tag or something else it doesn't understand and it's skipping it.

  • Registered: 2007-07-23
  • Posts: 86

Re: 0.08: Audio stuttering during skipping song

The files are local, it happens only when the output is an "Aggregate device". Or maybe when such device is made also of a Soundflower virtual output?