Trouble syncing multiple audio channels

Aug 16, 2010 at 11:41am

Trouble syncing multiple audio channels

Hi,

I’m doing an installation in which I need to play 4 channels of audio in sync with a qt movie file.
When I run the 4 channels as separate mono channels using sfplay~ I end up with the precedence effect whereby the sound appears to be coming from the channel that is triggered first.

If I just save the audio with the qt file then it doesn’t separate it out into 4 channels.
When I saved my audio file as a 4-channel file and tried to run it using ‘sfplay~ 4′ I couldn’t get anything to happen.

What would be the best way to go about doing this so that I ensure that all channels are triggered at the same time?

Thanks

#51802
Aug 16, 2010 at 12:11pm

sfplay~ 4 does work (it works for me since many many years), but you may need to adjust the buffer size (although I though I wasn’t necessary with Max5 anymore…). Check [p "More features"] in sfplay~’s help file.

Syncing the audio with the video is another story! Isn’t it possible to have 4 audio channels in a QT movie?

p

#185924
Aug 16, 2010 at 2:03pm

Thanks for the advice. Maybe i’m missing something really obvious but I’m just not getting any output from the ‘sfplay~ 4′. I’m simply loading a 4-channel wav file into it and then sending a ’1′ to trigger it. Is there something else I should be doing? (obviously the output of this is going to ‘dac~ 1 2 3 4′ and it does work with stereo/mono files)

#185925
Aug 16, 2010 at 9:04pm

bump

#185926
Aug 17, 2010 at 8:34am

No need for a bump!

Well, I never tried with a 4 channel WAV file (I always use AIFF files), and you’re right: it doesn’t work! Try to convert your file to AIFF…

Interestingly, sfinfo~ doesn’t return any sampletype information for my file.
As it doesn’t work with Max 4 neither, I first suspected my conversion to WAV to be wrong, but other softwares, like QT7, do work with my file.

I tried only briefly on X.6.4, Max5.1.4 & Max4.6.3.

Maybe time for a bug report…

p

#185927
Aug 17, 2010 at 8:34am

No need for a bump!

Well, I never tried with a 4 channel WAV file (I always use AIFF files), and you’re right: it doesn’t work! Try to convert your file to AIFF…

Interestingly, sfinfo~ doesn’t return any sampletype information for my file.
As it doesn’t work with Max 4 neither, I first suspected my conversion to WAV to be wrong, but other softwares, like QT7, do work with my file.

I tried only briefly on X.6.4, Max5.1.4 & Max4.6.3.

Maybe time for a bug report…

p

#185928
Aug 17, 2010 at 11:19pm

Hi,

sfplay~ 4 channel .wav playback works for me on 5.1.4, OS10.6.4

#185929
Aug 18, 2010 at 8:12am

Dave, thanks for your answer. But I still think something is wrong with 4 channels WAV.

I created a short 4 tracks WAV in Max with sfrecord~. The file can’t be read by audio softwares (like Snapper, QT or Audacity) except by Max itself. But even with Max, the preview in a File Browser doesn’t work (error -208, i.e. badFileFormat).

So I checked the header of the WAVE file. I think there is something wrong in the ‘fmt ‘ chunk: Max creates a WAVEFORMATEXEXTENSIBLE structure, where the cbSize and samp/bits fields should be 2 bytes, but it looks like 4 bytes are used. On the attached picture, the green selection (bits per samples) should be 10 00 but is 00 00

But I may be totally wrong, it’s probably too early for me to watch hex codes…

p

#185930
Aug 18, 2010 at 8:13am

Oopps, I forgot the picture. Here it is

[attachment=139131,985]

Attachments:
  1. fmt.png
#185931
Aug 18, 2010 at 3:16pm

Thanks Patrick. You definitely seem to be on to something there. I tried it with an AIFF file and it worked perfectly. Seems to be a problem with WAVs.

Alex

#185932
Aug 18, 2010 at 11:33pm

Yes Patrick you’re right about sfrecord~. There’s something about the way it writes the header of a 4+ channel .wav that makes other programs, e.g. Audacity, reject the file.

sfplay~ seems to have no problem playing back .wav files generated by sfrecord~ or other apps.

#185933
Aug 19, 2010 at 8:25am

Dave,

sfplay~ does have problems playing some 4 tracks .WAV, that’s the reason why this topic started (I attached one that works in QT, DP, Audacity but not with Max).

I continued to check the bytes of .wav files. It seems to me that sfplay~ plays correctly .WAV files created with a WAVEFORMATEX structure (i.e. wFormatTag = 00 01) but not those with a WAVEFORMATEXTENSIBLE structure (i.e. wFormatTag = FF FE).

The .WAV file format is a nightmare…

p

Attachments:
  1. 4sndSnapper.wav
#185934
Jan 18, 2012 at 9:16am

I’m afraid nothing changed in Max6…

A 4 track .wav file saved in Max 6 with sfrecord~ still can’t be opened in other softwares. And the small file I uploaded in my previous post still can’t be read by sfplay~.

Even the error messages (-208) from the File Browser are still there when trying to preview 4 tracks wave file made in Max.

Test with Max6.0.3 under OSX.6.8.

#185935

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