Variable FPS MPEG-1 File

[Logis]

Hello,

I've got a MPEG-1 file that I want to fix so that I can convert it later. So far it plays fine on Media Player and Media Player Classic but when I go to convert it or extract any of the tracks I come to an problem.

When playing it in Media Player I can see via the statistics that the FPS rate is varying and this means that whenever I try and extract it, it makes it static again and means that the video is far shorter than the audio track.

I have tried shrinking the audio track to match the video but then it just plays far too quickly and then goes out of sync later on.

I have tried VirtualDub, dgmpgdec, MPEG Video Wizard, Several Media Fixers and even screen recorders to try and get a file that works but all too no effect.

The file is MPEG-1 320x240 (supposedly) 29.97fps, should run for 5:51 but when extracted shows 3:34. The audio is 22Khz mono 160Kbps MP2 and is the correct length.

Any ideas on how to sort this problem out, as I'm out of ideas. Also sorry if this is the wrong part of the forum I couldn't see any other parts that seemed suitable.

Thanks

[jagabo]

Open it in VirtualDub. Set the Source Frame Rate to 18.27. Video -> Frame Rate... -> Source Rate Adjustment -> Change to [18.27] frames per second. That will make the running time correct but depending on how the variable frame rate occurs it may not be in sync all the way through the video.

Could you make the MPG file available somewhere. I'd like to take a look at it. I've never seen a variable frame rate MPG1 file.

[Abond]

I think there is no application in the world that can produce such a file.
Load the mpg in VDubMod, move the slider to the end of the file and write frame number. Now load the extracted video (m1v I suppose) in VDubMod and look at the frame number at the end of the file. I bet they are equal.

[jman98]

[quote="Abond"]I think there is no application in the world that can produce such a file.
/quote]

That makes sense as I've never heard of such a file either.

Be warned that the "genius" who produced this is yet another moron who thinks that by using 22 KHz audio, he has saved half the space that a 44.1 KHz audio file would take up. Expect the audio to sound like crap when you convert it to either VCD or DVD.

[Logis]

I have tried that in VirtualDub setting it to 18fps and indeed it makes it the same length but it is out of sync.

But in order too test it I have too extract the audio using another program as VirtualDub brings up "Error decoding MPEG frame 0 (0:00): incomplete frame" and then add the track from elsewhere. On playing the MPEG file in Media Player Classic it starts dropping from 29fps straight off and then hovers around 17fps, though jitter goes up to 20ms (not that I have a clue what that means) then it goes up and down again 19, 20 fps then back down it's all over the place.

The frame number is the same for both files 6433, but then it's not ever saying that the length of the film is longer only when I play it back does it match the length of the audio.

Could it be Media Player itself that is changing the FPS to match the audio?

[lordsmurf]

I think there is no application in the world that can produce such a file..

Application? Maybe not. Hardware? There sure is.

You've probably never dealt with DVB material before. It's hell to work with, it takes voodoo and luck for some of those awful transport files.

[Logis]

Any ideas on how too make it work then, Lordsmurf?

[Abond]

You've probably never dealt with DVB material before. It's hell to work with, it takes voodoo and luck for some of those awful transport files.

This is correct, I never dealt with DVB transport files. OTOH I thought these are mpeg2 type (as far as mpeg compression is concerned) and not 320x240

Any ideas on how too make it work then, Lordsmurf?

It is not clear what you want to do with it, but if you try to determine the duration of the elemetary mpeg video file simply playing it in software player, then it would not give you the right time. Why MPC changed the playing rate I have no idea, but you can be right here for matching the weird audio.

[jagabo]

I would try AVISynth's DirectShowSource() with the convertfps=true argument.

DirectShowSource("file.mpg", fps=29.97, convertfps=true)

If necessary, replace 29.97 with whatever the nominal fps of the file is. This always works for me with variable frame rate WMV and RMVB files.

[lordsmurf]

DVB in Europe is all over the place in terms of resolution.