Stuttering problem when rendering to WAV file with FLACs

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Larry Hastings
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Joined: Tue Jan 08, 2008 3:58 am

Stuttering problem when rendering to WAV file with FLACs

Post by Larry Hastings »

I'm using Multisequence 2.55 just for audio mixing. Most of the time that I play an audio file, there's a bit of stutter right as the file starts. (Heck, it might be all of the time, and I just don't notice when the file starts quietly.) I've never heard it stutter in the middle or end, just at the beginning, and seemingly only the first time a file is played. I'm mostly playing FLACs, so I don't honestly know whether or not it happens with other files.

The PC is an Athlon 64 x2, 4400+, with 3GB of RAM, so it should certainly be able to handle three or four audio streams. As it happens, Multisequence can't even handle two. And when doing non-real-time rendering! If I use "Save as audio...", I get the same exact stutter.

This sure seems like a bug to me. So I created a test case, which you can download here:
The zip file contains a Multisequence project, two FLACs I used for input, and the output WAV file Multisequence produced (which I also converted to FLAC to save on space). Note the stutter on both the whistling and the speech (but only the first time).

Whaddya think?

larry

GoldWave Inc.
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Re: Stuttering problem when rendering to WAV file with FLACs

Post by GoldWave Inc. »

Multiquence does not support FLAC files (not directly anyway), so it may be caused by a DirectShow FLAC decoder that is being used to handle the files indirectly. Make sure you have the latest version of the DirectShow FLAC decoder installed. The only other solution would be to convert the FLAC file to a WAV file using other software before using it in Multiquence.

Chris

Larry Hastings
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Joined: Tue Jan 08, 2008 3:58 am

Post by Larry Hastings »

You were right; I had picked up DirectShow FLAC filters from the illiminable Ogg filter set, and those are what gave me the stutter, even in GraphEdit.

I upgraded to the madshi FLAC DirectShow filters:
http://forum.doom9.org/showthread.php?s ... 8&t=130498
Now FLACs play in GraphEdit correctly; I can drag & drop a FLAC onto an empty GraphEdit graph and it'll create a lovely "madFlac" decoder for me. But Multisequence no longer recognizes FLAC files. I had thought that if it worked in GraphEdit it would work in Multisequence?

Thanks,


larry

Larry Hastings
Posts: 4
Joined: Tue Jan 08, 2008 3:58 am

Post by Larry Hastings »

I emailed Madshi, the author of madFlac, and he had this to say:
[...] my first guess would be that Multisequence maybe doesn't like the format madFlac reports on its output pin. There are 2 possible ways to report "PCM" output. The first one is setting the "wFormatTag" field of the audio format structure to "WAVE_FORMAT_PCM". The 2nd one is to it to "WAVE_FORMAT_EXTENSIBLE". Microsoft recommends using the latter solution and that's what madFlac is doing. [...] I'd suggest that you ask the Multisequence guys whether they accept WAVE_FORMAT_PCM or WAVE_FORMAT_EXTENSIBLE or both or none?
Which format(s) do you accept?

Thanks for your time,


larry

GoldWave Inc.
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Post by GoldWave Inc. »

Multiquence uses the SetFormat() function on the media stream to set the output format to WAVE_FORMAT_PCM. If the filter does not support that, then the file cannot be opened in Multiquence. Usually WAVE_FORMAT_PCM is the one thing that everything supports, so it would be unusual for a filter not to support it.

Chris

Larry Hastings
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Joined: Tue Jan 08, 2008 3:58 am

Post by Larry Hastings »

The latest release of madFlac supports WAVE_FORMAT_PCM. It works great with Multisequence! Hooray!

You can get it here:
http://forum.doom9.org/showthread.php?t=130498


larry

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