Problem reading .mpg files with recommended editors

[jr_2005]

I'm not entirely sure this is the site I need - I found it last week during a Google search. Perhaps one of you chaps could put me on the right path?

To be as brief as possible, I was searching for detailed information on the format of .mpg file headers. (Although a complete video novice, I am a C programmer and used to manipulating files at the binary level. I have previously been successful at fiddling with .mp3 files, once I found the header information.) Why do I want to mess with files at this level? So that I can do primitive cutting and splicing of a video file that I made some time ago. (Made with MGI VideoWave - I don't want to use this program to edit the file again as it seems to insist on re-coding the data; all I want is a simple editor so I don't get more quality degredation.)

So I found your site! I thought it was Christmas! (Well actually, it was...) As I only intend to play with these files about once every 6 months, I cannot justify the expense of buying software that would do so much more than I need, so I concentrated on the freeware programs. After scouring the forums and reading many of your guides, I thought that Videodub would be suitable. Unfortunately, as I was reading up the details on their website prior to downloading, I spotted that althought it could read mpg files, it could not write them (the program being targetted mainly at avi files).

OK, skip that one (as my file is a .mpg) - next choice which gets plenty of recommendation was Cuttermaran. So I downloaded and installed it. Looks good so far - lets try to edit my file. What's this - the file open menu has video file filters of .mpv, .m1v or .m2v . No mention of .mpg and sure enough, it can't see my file to open it. Hmm. Can't see any way of changing this file filter either.

Next. Move across to another popular editor - Mpeg2Schnitt. Taking a bit of a plunge into the German language website, I downloaded, installed and (thankfully) found the button which turned most of the text into English. Right. Here we go. Run the program - hang on a bit, where's my file? It is still being ignored by the file open filter.

It was at this point that I got that uncomfortable feeling. You know, the one where you walk into a pub in the middle of Yorkshire to order a pint and all the locals stop and look at you as though you had ordered bulls' blood or something. (Apologies to any rural Yorkshiremen over 70 reading this.) It was dawning on me that what you guys call mpg files and what I call mpg files are not actually the same thing at all! No matter how much I browse your forums and guides they always come back to the same editing suggestions - for programs which cannot open my mpg file. (We're not talking about corrupted files here; they can't even see the file to open it.)

What am I doing wrong? I must have a fundamental misunderstanding somewhere. Is your mpg stuff strictly in a DVD context and not applicable to other types of mpg data?
Alternatively, can any of you point me in the right direction so that I can try to hack the file myself? (I have made some small progress; the file seems to be made up of a header followed by fixed-size blocks of 2324 bytes each - unfortunately a quick check on my calculator shows that 13 of these blocks corresponds to 3 frames of (25 fps, 576 lines) video... clearly not quite as simple as a one to one mapping. (No doubt something to do with a mix of audio frames, I, B and P video frames. See? I have been reading up about it. Not learned much more than that, though...) I would probably try to cut/join the file at these block boundaries and hopefully end up with something useful, but it would be nice to know exactly what I am doing. In particular, cutting/joining at an 'I' frame would (if I have understood things well enough) give the cleanest results.)
Any suggestions would be much appreciated.

JR

[grossjamesh]

Do a GOOGLE searc for "mpeg file headers".

[jr_2005]

That's exactly what I did, and found this site...

JR

[BJ_M]

use mpeg2vcr to edit with ... will not re-encode

[Safesurfer]

I believe the two programs you mentioned, Cuttermaran and Mpeg2Schnitt., require you to use elementary streams. This means you have to demux your MPEG file into separate video and audio files - usually results in a .M2V file for the video, and AC3, MPA, or Wav for the audio. There are several programs in the Tools section here that will demux.

One other program that seems to get high ratings is Videoredo, but I don't know if that requires elementary streams as well.

[jr_2005]

use mpeg2vcr to edit with ... will not re-encode

OK just tried this. It wasn't on my original selection as it's trialware, not freeware. Means I'll have all these problems again in 6 months.


Hmm. It can read my file, but it's not at all happy with the interlacing - seems unable to cope with it at all. I'll try reading the help, again. Have to try again tomorrow for the actual editing process.


JR

[BJ_M]

mpeg2vcr has no effect on interlacing (in the output) -- the display window is a low(er) resolution display

[jr_2005]

I believe the two programs you mentioned, Cuttermaran and Mpeg2Schnitt., require you to use elementary streams. This means you have to demux your MPEG file into separate video and audio files - usually results in a .M2V file for the video, and AC3, MPA, or Wav for the audio.

Ah.. now we're getting a tad more involved than I was hoping for. BTW, I'm sure I have seen .m2v files playing video and audio together?

Might try Videoredo if I don't get any joy with mpeg2vcr. Gosh, my system is getting a bit cluttered with not-so-useful programs...

JR

[tekkieman]

One other program that seems to get high ratings is Videoredo, but I don't know if that requires elementary streams as well.

I don't think so. I've used the trial with VOBs.

[wonderuss]

Have you tried the mpeg tolls section on Tmpeg, i've used this many times for cutting mpeg files.

[jr_2005]

Just a final note to finish this thread off. I've spent the past few days downloading and installing all sorts of programs to try to perform my original task - which was simply to cut/join mpg stream (video + audio) files. I've learned quite a lot.

In the end, most of the programs were not useful to me for one reason or another. The only tool to work reasonably well was mpeg2vcr, but as I mentioned earlier since I won't be doing this type of task very often I can't justify the cost of converting this trialware into full software. So I will have the same problems in 6-12 months time - hopefully by then there will be a freeware program to perform this rather basic set of functions.

Thanks for all the tips and advice.

JR