MPEG-1 To Divx/Xvid

[bugmenotwillyou]

Hey everyone well i have a little problem i have a bunch of old TV Shows on my HD that are around 300-400MB MPG files which takes up a bunch of room so im looking to convert them to xvid/divx and i cant really find something that does it right. and if do convert them will they be smaller because in the past i have tried and it made them huge(er) so if anyone could tell me a good encoder to do this. Thanks!

[Guest]

I've just released a beta of DGMPGDec that supports MPEG1. You may use that for your decoding and serving via Avisynth to the transcoder of your choice (e.g., VirtualDub).

http://forum.doom9.org/showthread.php?p=663990#post663990

You can get compression gains by reducing the bitrate for your encodes and possibly compressing the audio further. You can also reduce the resolution (picture size) of the video. You'll have to assess whether the quality will suffer too much.

[phædrus]

neuron2, I think your new dgmpgdec version may be a big help to me. I have a problem similar to the first poster, but with a complication.

A friend gave me two MPEG1 files of captured TV shows. But they appear to have been inverse telecined without being decimated. Every fifth frame repeats, except perhaps for a few points when reception breaks up a bit -- that might disturb the pattern.

If I demux with DGIndex, re-encode the audio, would I be able to frameserve the video to VirtualDub and encode to DivX with just a command to "decimate()" in AviSynth -- would that fix the repeated frame problem?

Sorry if this is a stupid question, but I didn't see any guides that helped with this kind of correction after the fact (an improperly done capture -- dummy did not decimate the duplicate frames) nor have I worked much with MPEG1.

[Guest]

If I demux with DGIndex, re-encode the audio, would I be able to frameserve the video to VirtualDub and encode to DivX with just a command to "decimate()" in AviSynth -- would that fix the repeated frame problem? Yes, of course. But there is no need to re-encode the audio, because Decimate() will not change the running time of the movie.

It's just this sort of problem that motivated adding MPEG1 support. :)

Please advise if you run into any difficulties.

[phædrus]

DG, I did have a problem. I demuxed the mpeg file, fed the d2v to avs and decimated the video, encoded to DivX with VDubMod. But when I muxed the original .mpa audio back into the .avi file, the thing got progrssively more and more out of sync. Decimate seemed to work perfectly on the video, making motion smooth as real life by removing the duplicate frames. However, the sync was OK in the beginning, but after about 7 minutes (the length of the test clip I made), the video was about a second behind the audio. What would be the most likely causes of this? It is like occasionally too many frames are decimated, and this is causing the video to lag behind. Huh?

BTW, I am using a version of decomb that is probably a year old or more. I don't know if that would make a difference. I'm going to download a more recent version, assuming there is one, and try that, but I kind of doubt that is the problem.

[NaN]

Are you using VDubmod >1.5.4? AFAIR newer versions as 1.5.4 have synch problems.

Cheers, NaN

[Guest]

There's no need to demux the video. Just do Save Project to make the D2V file.

Do this: Serve the AVS script (with decimation) into VirtualDub and then look at the File Information dialog. Get the time duration reported for the video.

Then open your MPA in Media Player or whatever and get its time duration. If the two are the same, then the transcoding application must be causing the problem.

You can also convert to WAV and then use regular VirtualDub and see if that works any better.

[phædrus]

You can also convert to WAV and then use regular VirtualDub and see if that works any better.

Actually, I tried that. But for some reason this new version of DGIndex does not convert this particular MPA audio to WAV. It basically ignores the instruction as far as I can tell. Is that a bug? I tried it on VOB files and it works normally -- this is the process I normally use -- make a d2v file, and convert the audio to WAV. Then I compress to 128kbps cbr MP3 to merge with my DivX video. That works perfectly well, but not with the MPA audio track on this MPEG1 file.

[Guest]

Try 1.4.0b5. There are two ways: demux the MPA and convert to WAV with BeSweet. Or Decode to WAV in DGIndex. Try both and tell me if they work.

[SeeMoreDigital]

If you're interested, you could use an application called MPEG Mediator....

Although it's quite old and not supported anymore, it is very good at converting Mpeg1 to Mpeg4 (XviD, DivX etc with MP3 audio). And there's no need for you to carry out any stream de-muxing before hand.

Altering the aspect ratio of the input file can be carried out, as well as cropping and re-sizing via the "Filters" tab....

It's a real shame there's not a modern equivalent of MPEG Mediator :(


Cheers

[dragongodz]

*COUGH* DVDx can do it aswell *COUGH*

[phædrus]

Thank you neuron2, I got the latest version, and tried the "decode to WAV". As far as I can tell, nothing happens when this is checked, except the d2v is created, but no WAV file. Then I tried the Demux (AC3, MPA, DTS) option and got my MPA file.

Then I checked the timing. The timing of the original MPEG file is said to be 42:54 in Windows Media Player. But the MPA audio file is only 42:40.

That said, when I tried before to merge the audio with the DivX video created with VirtualDubMod the audio started out in sync, but got progressively worse. So I don't think using plain VirtualDub would solve the problem. I don't know the source of this time discrepancy. DGIndex is putting out an audio file that is shorter than the original video, apparently. There must be a problem in the original video that is causing DGIndex to read it this way, and probably it is getting beyond my level of skill and/or patience to fix it. :-)

But if you have any suggestions that are simple to implement, I'm still curious about the cause of this glitch.

[Guest]

If you want to upload the original MPEG file to my FTP server I will figure it out for you. See my sig below for access details. Inform me here of the filename that you upload.

[video]

bugmenotwillyou don't know what kind of mpeg-1 files do you have. if they are in standard vcd format 352x240@29.97 or 352x288@25Hz after changing audio rate from 441k1 to 48k you may burn them into DVDs. an mpeg1 to mpeg4 ASP video transcoding may end up a huge quality loss.

[phædrus]

If you want to upload the original MPEG file to my FTP server I will figure it out for you. See my sig below for access details. Inform me here of the filename that you upload.

Thanks, DG. Unfortunately, I'm one of those poor unwashed who doesn't have broadband at home. Perhaps within the next week I can get access to a good connection and transfer the file to you. Thank you for your time and patience.

phædrus

[Guest]

Unfortunately, I'm one of those poor unwashed who doesn't have broadband at home. You're seriously handicapping yourself. :)

If you want to snail mail it to me on a disk, send me a PM. I'll definitely be able to resolve the issue if you can give me the file.

[Pyscrow]

Is it worth converting Mpeg1 to DivX?

I have had a bit of a play, (not seriously) in the past and found that I dont get much of a file size reduction doing so.