Hello,

I'm trying to play the sound file to a corresponding video file in sync with one another. I tried just linking a bang to both the sound and video files; however, it sounds as though the sound is playing at a slower rate. There is a noticeable pitch shift from when I play the file in quicktime. Also, even though the video and audio are out of sync they tend to lag together. I read that the pdp_qt~ object would be able to sync the sound, but when I used it I got an error (error decoding audio). I also read that specifying the frame rate in the gemwin object would assuage the situation. No such luck for me.
Here is my patch and I thank anyone in advance for any light they might shed for me.

-Y

http://www.pdpatchrepo.info/hurleur/AudioVideo.pd

To be clear I installed X11 to be able to use pdp_qt~. It sort of works. The sound and video are in sync; although, they play progressively more slowly and choppy as the video progresses. I still get the error pdp_qt: error decoding audio in the PD terminal.

That patch looks like

[bang(
|
[openpanel]
|
[open $1(
|
| [play(
| /
|/
[pdp_qt~]
| \ \
| [dac~]
|
| [create(
|/
[pdp_glx]

Hi ylagandre,
is it possible that the audio you are using is sampled at 48Khz and your pd project is playing it at 44.1Khz? I say so because usually the audio for video is 48khz and you say it's playing pitchshifted...

Hello alistar,
Yes, indeed that was part of the problem and I thank you for your response. The pitch shifting issue is gone.
On the other hand it still doesn't quite play in sync in the first patch. In both patches the audio and video slow down to start and stop one frame at a time and then suddenly play again at normal speed intermittently. This happens whenever I play audio and video files simultaneously in Pure Data. It even occurs when I play a video file in one patch and a sound file in another patch.
I tried increasing the latency under the audio preferences, but to no avail. The sound will play fine on its own while the video will persistently start and stop when I play it by itself. Is there a way to allocate more resources to video play back in GEM?

well, I always experienced troubles while playing audio and video together in pd (gem or pdp). I red in this forum to open two istances of pd one for the video stuff the other for the audio but I never tried it.
http://puredata.hurleur.com/sujet-6244-send-netsend