MPEG2 (DVD) question: Can re-encoding eliminate macroblocking?

[strangelove91]

Hi folks,

I have a question, and wasn't able to find any real answers through Google (by the way, am I the only one thinking that Google search results are getting less and less relevant?)...

Anyway... I have an MPEG2 file which was taken from a rather bad DVD rip. Whoever did the ripping was an idiot - the DVD file structure is borked. I was able to extract the raw MPEG-2 file with ancient version of TMPGEnc DVD Author (which somehow works as a portable program on Win7), only to discover that there's occasional (yet noticeable) macroblocking in the image. I suspect that the original was recorded on a DVD-9, and the ripper used a cheap, crappy encoder to do a rush job on a DVD-5 conversion.

I am really bothered by the macroblocking, and I'm wondering if it can be "smoothed out", perhaps by reencoding the file with another piece of software - and I'd like to keep the file as MPEG-2, which would allow me to recreate a DVD which could be shared with others.

Is this feasible, or just wishful thinking?

[jagabo]

You can't remove the macroblocking by simply reencoding. But you can use a deblocking filter and then reencode. You might as well use a deringing filter too. Of course, detail won't be restored. The blocks will be replaced with smooth gradients.

[strangelove91]

@jagabo:

Thank you for the reply!
Smooth gradients are preferable to the current blockfest... do you happen to know if the TMPGEnc software suite has any deblocking filter? If not, what software solution do you suggest?

I was originally hoping the procedure would be as simple as using DVD Rebuilder and specifically asking the program to use a deblocking option (if it exists)...

Otherwise, I've seen that for this type of scenario some people suggest using VDub with one of the deblocking filters here - http://www.compression.ru/video/deblocking/index_en.html or http://www.compression.ru/video/deblocking/smartdeblocking_en.html ... But that would require saving he resulting file asn AVI, then reencoding it as MPEG2....

[jagabo]

I don't know if TMPGEnc has a deblcoking filter. I would do it using the DgMpgDec package for AviSynth. Build an index file with DgIndex, then open the file with Mpeg2Source("filename.d2v", CPU=6) -- CPU=6 enables both the deblocking and deringing features. If you prefer less aggressive deblocking you can use Deblock_QED() in AviSynth. I'm pretty sure TMPGEnc will accept AviSynth scripts.

[strangelove91]

Thank you once again for posting.

I'm a complete n00b at this, so could you please walk me through the procedure?

1) download DGMPGDec and AviSynth
2) drag the video into the DGIndex window... now what?

[jagabo]

Did you put a copy of DGDecode.dll in AviSynth's plugins folder? If not, do so.

Use notepad to create a plain text file in the same folder as the d2v file. Type in the text:

Mpeg2Source("filename.d2v", CPU=6)

Replace "filename.d2v" with the name of the d2v file you created. Change the extension of the text from .TXT to .AVS. Open the AVS file in your encoder. I usually preview scripts with VirtualDub.