Proposal for Open Source Compressed Domain Mpeg-2 Transcoder

[int 21h]

Most of us have heard of DVD2One. Basically it uses a process called Compressed Domain Mpeg-2 transcoding to reduce the size of a MPEG-2 stream so that you can author that stream later. I was unfamiliar with this process until the tool came out, but have now found a wealth of information about it.

Is anyone interested in a project, perhaps modifying an existing application (like DVD2AVI) to preform this process? It doesn't seem to be exceedingly complicated. Here are the links I've found so far:


http://www.cs.cornell.edu/zeno/paper.../transcode.pdf
http://www.hpl.hp.com/personal/Susie...7/hpidc97.html
http://www.ee.princeton.edu/~minwu/p...00_transcd.pdf

[mpucoder]

Judging from what I've seen and heard, DVD2one gets excellent results. We all knew there was an easier way than decoding and encoding to reduce the bitrate, now someone has done it.
I don't know about modifying an existing program, unless it was designed for mpeg in and out. I think a standalone app along the lines of ReMPEG2 (which this would replace) would be more acceptable.
I'm in. First thing to do is get webspace. SourceForge is a good place for this, as long as the project is open source, it will be welcome there. I can also supply webspace if that's not enough (we're upgrading the mpucoder servers now to be co-located, and IfoEdit interest is tapering off, so there's plenty of bandwidth)

[Olebrumm71]

Here is another interesting web-page on the subject of transcoding of MPEG2 videostreams:

http://www.bbc.co.uk/atlantic/transcoding.html

[int 21h]

Well, I can code C/C++, I just get lost in some of the more complex MPEG operations that go on (DCT, etc.). I will look into getting some space at Sourceforge a little later today. I would definitely want this to stay opensource and free as in beer, otherwise there's no point

[IdentDee]

Originally posted by int 21h
Well, I can code C/C++, I just get lost in some of the more complex MPEG operations that go on (DCT, etc.). I will look into getting some space at Sourceforge a little later today. I would definitely want this to stay opensource and free as in beer, otherwise there's no point

Perhaps we can use libvideocoding as far as i know it has everything but the bit allocation at transrating what we need.

rate control is the main problem. The activity in the macroblock must be derived from the dct coefficents. DVD2one seems to use a bitrate reduction factor on the quantization leading to lower perceived quality since it gives a damn on the activity in the macroblock.

http://rachmaninoff.informatik.uni-m...ing/index.html

[Nic]

Id love to help in this, but I just dont think ill have the time at present But -h is finishing his MS-MPEG-4 -> MPEG-4 converter, so maybe you can rope him in (sorry -h )

Ill pay close attention and help when ever I can

Cheers,
-Nic

[-h]

Yeah, not too surprisingly I've had my days off chewed up by other activities, so the convertor will have to wait until next Tuesday.

But yes I've been mulling over creating an MPEG-1/MPEG-2 encoder/decoder, and a side-effect of that would be creating some transcoding modes. There are a few ways it can be done, the fastest looking the worst of course, but that's what trial and error is for.

I've no idea when I can start working on it, so I may not be much use to this project

-h

[Ookami]

Aren't there two moderators, here, who worked (work?) on a free MPEG 1/2 encoder? Maybe they could/would help?

*cough* *cough*

As for alpha/beta testers, I think that should really be no problem .

Good luck and hopefully it will succeed.

Cheers,

Mijo.

[int 21h]

What if we could take bbMpeg and modify/optimize it? It already accepts Mpeg-2 input.. all we would need to do is make it smarter (& faster), to intelligently reduce our streams....

[Nic]

bbmpeg's code is a bit of a nightmare, decoding the mpeg-2 parts won't be a problem as the standard MSSG code or dvd2avi's code can be used to decode the bits we'd need, the writing of the bistream back out could be a bit fiddly. Then theres all the bits inbetween. Its not really everso hard, the main thing is its no minor task.

Unfortunatly I dont think any of us want to give up our free time to make a piece of free software which has already been created and making quite a lot of money for those who created it. Its a sad shame

Cheers,
-Nic

ps
mjpeg.sf.net mpeg-2 encoding source is a bit easier to read for me anyway...

[int 21h]

Let's make commercial software then

[Ookami]

Isn't this a more promising and interesting project than the n-th automated encoding app etc.? I understand that it is way more complicated, but no one says that it has to be done in a few weeks/months.

I just want to show that this project would be very interesting and wanted. Surely others (who don't read this forum, BTW), would agree.

Just look how VirtualDub has changed in the last few years. From a little and unknown GPL video app, it's now for sure the most important/best freeware application in this area.

If this ever starts (int21h, have you looked in the Sourceforge webspace?), you can count me in for beta testing.

Cheers,

Mijo.

[int 21h]

The SF space is no problem, We've gotten in the past for other stuff (Save-OE, Nandub, etc.), but no point in getting the space if I have nothing to put up on the space...

[Nic]

Isn't this a more promising and interesting project than the n-th automated encoding app etc.? I understand that it is way more complicated, but no one says that it has to be done in a few weeks/months.

Rarely is a truer word said. So you've convinced me, ive started to look into it. I dont know if ill just hit a brick wall, but ill look through and at least put some code down to pass a MPEG-2 and get some of the parts we need out of it

-Nic

[Nic]

http://www.cs.wayne.edu/~dil/research/mdc/

Ok some parts of that download might be useful...
from the readme:
ompressed domain feature extraction, such as motion vector extraction,
DCT components extraction.

I think some stuff could be learnt from the code there, but maybe im being too optimistic, ill report back after ive scurried through the code

Cheers,
-Nic

ps
Ahhh, the zip does not contain all the source code, ill email the author

pps
doh! its from 1999, the chances of getting a reply are slim. back to the drawing board.

ppps
On the libmpeg2 dev mailing list someone asked about dvd2one, it will be nice if the mighty walken responds

[int 21h]

[int 21h]

It contains all of the header files and the MDC.lib.. what else is needed?

A thought occured to me though... Does DVD2One pay the MPEG-LA patent fees?

[Ookami]

Yay! Great news, thanks to both of you...

Now, let's see if mpucoder and the others who've already showed interest, will contribute too. Not to mention that many new people could and probably will contribute too.

Can't wait to see the first Sourceforge steps (this will get me to update my programmers corner after a very long time )...

A happy wolf .

Cheers,

Mijo.

[Nic]

http://nic.dnsalias.com/MPEG2Enc.zip

Just for fun, while im doing "research" into it. Here's a Commandline MPEG-1/2 encoder that encodes from Avisynth AVS files.
(based on mjpegtools)

Tell me how it goes for you,

Cheers,
-Nic

[Ookami]

@Nic regarding MPEG2Enc

Umm, I doesn't work for me at all (at least in the short testings I've done)... What have I done wrong?

OS: Windows XP Pro SP1

Source: 768x576 25 FPS Huffyuv 2.1.1. CCE patch (no audio)

See the attached pix for the error report of the program (when selecting MPEG2 output). After I've selected MPEG1 for output, I've got a 383 KB file wich produces, on playback, just a green screen.

After choosing a Xvid AVI 640x480 (with audio), the program does nothing at all (mpeg1 and 2)...

Same when choosing a DV AVI (720x576).

Thanks for your researching .

Cheers,

Mijo.