mpeg videos not seekable

[piktun]

Awhile ago I used direct show dump utility to convert .tivo files to .mpeg. Fairly recently I had decided that I was going to burn these videos to clear up space on my hard drive and have back-ups but I rather quickly ran into problems, mostly with quality. Anyway I have come back to tackle this again and figured that I would start with trying to fix the fact that the videos are not seekable.
I searched for information before I posted and found alot for wmv and asf files but hardly anything for mpeg files. Is there a program like asfbin for mpeg files or what is the best way to fix my problem?

[Baldrick]

Videoredo using the quickstream fix.

Or if you want a free solution it might help to "run" them through pvastrumento or projectx or mpg2cut2 or avidemux.

[JohnnyMalaria]

For DirectShow, MPEG is not seekable because it doesn't have a fixed frame size. The mastermind behind DirectShow - Geraint Davies - has developed an MPEG parser filter that can seek. He provides the VC++ project source code at http://www.gdcl.co.uk/articles/ but since source code isn't of much help, I have just built the DirectShow filter from it (SampleParser.dll). Just register it like any other DirectShow filter.

I don't know if any software will use it by default but you can use GraphEdit to play the MPEG files using this seek-capable filter. I've just tried it an it worked like a charm. You could probably change the merit to make it override the default MPEG parser.

sampleparser.zip

[piktun]

Since I want to fix these files and not just play them, will the programs Baldrick mentioned in the first reply work to fix this problem, or how do you fix a file that does not have a "fixed frame size"?
thanks

[JohnnyMalaria]

By frame size, I didn't mean the pixel dimensions. I was refering to the number of bytes required to stored the compressed image. Sorry to confuse.

[Midzuki]

JohnnyMalaria forgot to mention that
SampleParser.dll depends on Msvc?90.dll.

[JohnnyMalaria]

Oh. It's because of the version of Visual Studio I used.

I could rebuild it statically if there's interest then there'd be no dependencies.

[piktun]

I am a novice with the whole video editing thing but I am assuming that SampleParser.dll and Msvc?90.dll are intended to fix the direct show dump utility? Regardless that is of little importance as I guess I should have mentioned that I no longer have the .tivo files. I only mentioned how the mpeg files came to be not seekable figuring that information might be helpful in fixing them.

Which brings me back to the question, what would be the best way of fixing these videos?
thanks

[JohnnyMalaria]

Whether an MPEG file is seekable depends on the software rather than the file itself.

Programs that use DirectShow to do the grunt work use a series of so-called filters that perform different functions. The first reads a frame from the file. The next step for MPEG usually converts the file data to a valid MPEG stream. After that, the stream has to be split (parsed) into an audio stream and a video stream. Each of these is then decoded to give the final audio and video. The program uses these to show on the screen or encode to a different format etc. If the program wants to seek, it passes a request down through the filters but each filter must support seeking. The standard Microsoft MPEG parser doesn't. The filter I refered to does. Note, it is intended for MPEG-1 only.

Have you been able to seek other MPEG files with the same software you are using now?

If you convert the MPEG files to WMV, the WMV should be seekable. Actually, good old Windows Movie Maker can be very helpful here. I've just tried it. Drop an MPEG file onto the WMM timeline - you can scrub it. Then you can export it as WMV which, in Windows Media Player, is seekable.

Note, this is all for MPEG-1. I haven't tested it on Vista - WMM supports MPEG-2 on Vista IIRC.

[piktun]

Yes, I can seek all the other videos I play (including other mpegs) using the same software (windows media player) that I am using for my problem videos. That being the case how can the problem not be with the files themselves?