I have a bit of a problem.

I'm running a Dragon system with a Chaintech AV-710 sound card and hd-5500 capture cards. The problem I'm experiencing is that I seem to be getting pitch shift. Sometimes the pitch is increased, more often it is decreased. When its a video that has been shifted, the video stays in sync with the audio, so apparently the whole thing is stretched.

Some things I've observed:
It affects maybe one in five recordings, rough estimate?

It seems to be specific to a recording; if I notice something has been shifted I can stop playback, play something else which is unaffected, and then play the original recording and it will still be shifted.

It doesn't seem to be just video recordings; it affected my mp3 playback (from mythtv) at one point. It was affecting all mp3s at that time, but this has not persisted. This has only happened the one time.

It happens to both digital and analog recordings.

On a digital recording that was affected I played with Mythtv's time shift function. Speeding up or slowing down playback had no affect on the pitch (although it did change the audio away from passthrough when playback was something other than normal speed; I assume this is normal behavior).

Restarting the computer does not fix the behavior.

Any ideas on what might be causing this? Thanks

My first guess is that some of your recording schedules have the time shift feature set to something other than 1.00. I'm not in front of a box right now, but in mythweb, you can look at your recording schedules and under the "advanced options" section of each schedule there's a pull down menu for "time stretch default." It should be set to 1.00 for playback in real time.

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Mike
My Hardware Profile

Thanks for the reply, mihanson; I checked the recording schedules, and everything is set to 1.00 time stretch default.

I saw interesting behavior today:
I went to watch a previously recorded show while another was in the process of recording. This show had higher than normal pitch. I tried other shows that I have played back before with no problems; the analog ones had raised pitch, and the digital ones played normally. I played a video (rather than a tv recording), and it had normal pitch. I played back the show that was in the process of recording, and it played normally. When the show finished recording (and another recording from the same channel started), I could play everything back everything with normal pitch, except for the show that had just finished recording, which had lowered pitch.

So, it seems that some recordings are putting the system into a state where "time slows down" for the recording, and everything else speeds up to compensate. Then when the recording is over, things go back to normal, with the recording being left in a slowed down state. This can happen during recordings from both analog and digital channels (since I have recordings from each that are "slowed"), but the compensatory "speed up" only affects analog recordings, and mp3 playback.

Have you enabled "Use video as timebase"?

Mike

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LinHES 7.4
Australian Dragon
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Enabling the "Use video as timebase" option apparently fixes the pitch of affected recordings, but the audio quality suffers, and the audio on digital recordings stutters badly.

I think I'm going to try upgrading to R5.5 one of these days (currently at R5F27), so maybe the problem will just ... go away? A man can dream.

What hardware are you using? You didn't mention this.

Have you also played with the extra audio buffering?

Mike

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LinHES 7.4
Australian Dragon
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- motherboard: Intel DG965WH
- audio: Chaintech AV-710 digital (s/pdif passthrough enabled)
- CPU: Core 2 Duo E6300
- graphics: Asus EN6200LE
- RAM: 2GB (2x1GB) DDR2-667 PC2-5300
- tuners: 2x hd-5500 (only one currently in use)

I haven't changed any audio buffering options; I can see tonight if that changes anything.