Author Topic: Decoding multichannel audio recorded with Fraps  (Read 7275 times)

Philos86

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Decoding multichannel audio recorded with Fraps
« on: March 16, 2012, 12:25:42 AM »
Has anyone managed to successfully open and convert multichannel audio footage recorded with Fraps? I haven't been able to get it to work at all. I'm assuming Fraps uses a multichannel PCM stream to store the audio in the AVI container; if that's true then I wonder why Avidemux can't open it.

nibbles

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Re: Decoding multichannel audio recorded with Fraps
« Reply #1 on: March 16, 2012, 03:08:39 AM »
Find MediaInfo Gui.  open the video.  Switch to HTML view.  Copy/Paste into a code block or gist so we can see what you have while we wait for someone who's done this before.  Tell us your exact avidemux version.  Some multichannel features may not be implemented yet.

Philos86

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Re: Decoding multichannel audio recorded with Fraps
« Reply #2 on: March 16, 2012, 04:34:46 AM »
Here's the codec info:

Code: [Select]
General
CompleteName                     : Test Capture.avi
Format                           : AVI
Format/Info                      : Audio Video Interleave
FileSize/String                  : 3.95 GiB
Duration/String                  : 2mn 25s
OverallBitRate/String            : 233 Mbps

Video
ID/String                        : 0
Format                           : Fraps
CodecID                          : FPS1
Duration/String                  : 2mn 25s
BitRate/String                   : 229 Mbps
Width/String                     : 960 pixels
Height/String                    : 544 pixels
DisplayAspectRatio/String        : 16:9
FrameRate/String                 : 60.000 fps
Bits-(Pixel*Frame)               : 7.311
StreamSize/String                : 3.88 GiB (98%)

Audio
ID/String                        : 1
Format                           : PCM
Format_Settings_Endianness       : Little
Format_Settings_Sign             : Signed
CodecID                          : 00001000-0000-0100-8000-00AA00389B71
Duration/String                  : 2mn 25s
BitRate_Mode/String              : Constant
BitRate/String                   : 4 234 Kbps
Channel(s)/String                : 6 channels
ChannelPositions                 : Front: L C R, Back: L R, LFE
SamplingRate/String              : 44.1 KHz
BitDepth/String                  : 16 bits
StreamSize/String                : 73.4 MiB (2%)
Interleave_Duration/String       : 996 ms (59.78 video frames)

I'm using Avidemux 2.5.6 (x86-64).

I'm not sure why Avidemux isn't capable of decoding 5.1 PCM tracks; Perhaps the build I'm using just wasn't compiled with the proper support?

Jan Gruuthuse

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Re: Decoding multichannel audio recorded with Fraps
« Reply #3 on: March 16, 2012, 01:50:29 PM »
Should work when audio settings in Fraps are set to Stereo. Upload an original sample recording +- 20 MB of a stereo  and a multichannel recording to an upload site like Rapidshare or similar and provide link here for assessment by developers.
« Last Edit: March 16, 2012, 03:28:55 PM by Jan Gruuthuse »

nibbles

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Re: Decoding multichannel audio recorded with Fraps
« Reply #4 on: March 16, 2012, 09:55:03 PM »
So you have a PCM stream with 6 channels.  Neat.  For some back-story, DVDs allow LPCM as we know:

PCM: 48 kHz or 96 kHz sampling rate, 16 bit or 24 bit Linear PCM, 2 to 6 channels, up to 6,144 kbit/s

But we see your audio stream is recorded at 44.1 kHz.  That's probably the blocker.  The multichannel audio data is a single stream of information, alternating channels every 996 ms according to your paste, L,C,R,RL,RR,Sub repeating.  You can see how it will break easily if it only gets 44,100 bits of data during that time, not 48000 if that's what it's expecting.  Maybe you can just resample your 6 channel audio to 48 kHz if you'd rather not loose the surround sound to stereo as Jan suggested.