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Author Topic: skipping when playing back iTunes m4a encoded files with heavy usage  (Read 3200 times)

e-head

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skipping when playing back iTunes m4a encoded files with heavy usage
« on: May 19, 2008, 04:31:42 pm »
I have a P4 2.6 GHz machine.

If I do a lot of browsing in MC12 when I'm playing back an iTunes m4a encoded file it will start to skip. Setting the buffer up to 5 seconds doesn't really help much. iTunes plays these files back fine, but it's UI becomes extremely sluggish. Maybe iTunes has a higher priority thread for audio playback, I don't know. I know these files tax the CPU more than mp3's.

My question:
Is there some sort of fiddling I can do with the DirectShow Filters or something that might help? Maybe iTunes uses a faster filter/codec or something? I'm no expert on these matters.

I assume if I had a 2.4 GHz Core 2 Duo this wouldn't be an issue.
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JimH

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Re: skipping when playing back iTunes m4a encoded files with heavy usage
« Reply #1 on: May 19, 2008, 04:36:12 pm »
By default, MC would use the Quicktime engine to play those.  This is probably also what iTunes does. 
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Alex B

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Re: skipping when playing back iTunes m4a encoded files with heavy usage
« Reply #2 on: May 19, 2008, 05:20:25 pm »
No problems here. I tried some heavy browsing and things like video thumbnail creation and searching for non-existent files during m4a playback. My playback bufffer was set to 0.5 s and I used a 2.8 GHz P4.

I use DirectShow for m4a decoding (instead of QuickTime). Here's my graph info:
Quote
Filter Graph Info (Graph for type: m4a):

    Filter 'JRiver Audio Renderer'
        CLSID: {EC1F74A8-7E55-4814-9F9F-D417489075CA}
        Host:
        Input Pin 'In'
            Connected to pin 'Out' of filter 'ffdshow Audio Decoder'
            Major type MEDIATYPE_Audio  Sub type MEDIASUBTYPE_PCM, Format type FORMAT_WaveFormatEx

    Filter 'ffdshow Audio Decoder'
        CLSID: {0F40E1E5-4F79-4988-B1A9-CC98794E6B55}
        Host: C:\Soft\CCCP\Filters\FFDShow\ffdshow.ax
        Output Pin 'Out'
            Connected to pin 'In' of filter 'JRiver Audio Renderer'
            Major type MEDIATYPE_Audio  Sub type MEDIASUBTYPE_PCM, Format type FORMAT_WaveFormatEx
        Input Pin 'In'
            Connected to pin 'Audio' of filter 'Haali Media Splitter'
            Major type MEDIATYPE_Audio  Sub type Unknown GUID Name: {000000FF-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx

    Filter 'Haali Media Splitter'
        CLSID: {55DA30FC-F16B-49FC-BAA5-AE59FC65F82D}
        Host: C:\Soft\CCCP\Filters\Haali\splitter.ax
        Output Pin 'Audio'
            Connected to pin 'In' of filter 'ffdshow Audio Decoder'
            Major type MEDIATYPE_Audio  Sub type Unknown GUID Name: {000000FF-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx

You should able to use the same filters by installing CCCP and enabling DirectShow playback for the m4a file type: http://wiki.jrmediacenter.com/index.php/MP4_and_M4A_File_Support
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e-head

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Re: skipping when playing back iTunes m4a encoded files with heavy usage
« Reply #3 on: May 19, 2008, 08:08:54 pm »
Thanks for the tip Alex, I'm going to give that a shot. I hear that CCCP is a good mega-codec pack.

Edit:
That worked!
Thanks a million. No more skips.
The cross fade in and out works now too.
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e-head

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Re: skipping when playing back iTunes m4a encoded files with heavy usage
« Reply #4 on: May 19, 2008, 08:16:53 pm »
Hey, one more question for you, since your system is close to mine.

Can you do 1080p video files fine? I have some 1440x1080 wmv9 files encoded at around 8000 kbps and they just kill me (soaring to 100% CPU usage quite frequently). One player does the video fine but chops the audio. Another player does the audio fine but chops the video. I haven't even tried MC12. I have a socket 478 and I can upgrade to a 3 Ghz P4 I think. Someone said this was about the "magic" spot for playing back 1080 stutter free. Just curious if you've tried it on your 2.8. Maybe those ffdshow filters will help?
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