Transparent transcoding of DVD to h264

[gnutellafan]

I have been ripping my dvd collection and storing the original mpeg streams with extras ripped out using dvdremake. Of course the space this consumes is getting pretty overwhelming and I am considering transcoding my collection to h264. My question is how transparently can I transcode, and what would the average size savings be at this setting, and is h264 mature enough yet to transcode my collection?

Thank you.

[Daodan]

Well, it is worth it of course. Even if x264 will get better in time, at the moment is still pretty impressive. The only problem I see in your case is that you seem to recode dvds already recoded using mpeg2 at a lower bitrate than the original. I don't know how good dvdremake is, I never tried it, but this way surely the source is already not so compressible. I do my encodes at 1/3 dvd5 (for around 2h movies) so in your case that would be 1/3 less space. And the quality is very good, almost hard to see the difference if the source was good and carefully cleaned before. The only thing is in this case the time, at the settings I use it's painfully long, unless you have a dualcore (it's still long with one of these too). You're the one that has to decide if time/quality/space factors are worth it.

[gnutellafan]

I have the original MPEG2 streams (just ripped extras), I have not transcoded or downsampled anything. Of course the original compresion of the movie to MPEG2 was a lossy process and I know it wont get better to go to h264 but I want the picture to be just as good as the original dvd.

[Doom9]

well.. transparent = lossless in my eyes ;) And x264 can do that. If you go any lower than lossless, it's up to you to decide what quality levels are acceptable to you. If final size is of little concern, you can stick to using -crf, it should allow you to get comparable quality regardless of the source (but on the other hand the size varies with the complexitiy of the source).. so you pick the crf parameter you can live with, and encode all your content with the exact same settings.

[Daodan]

Like Doom9 said, to have 'just as good' use lossless (but the file will be huge). It can't look the same, whatever settings you use, even if you transcode them to the same size of the original. First of all there is that small 'moving noise' (I don't know the official word) that you will always lose, even if you disable the inloop debloacking filter. The thing is to find something 'as close as possible'. As I said, 1/3 dvd is very good, and 1/2 there is hard to see any loss in detail (except some of that noise as I said, but I wouldn't really call that a bad thing) unless you watch your movie really close to the monitor.

[gnutellafan]

Wouldnt transcoding to lossless from a lossy source actually result in a bigger file, which is also probably more CPU intensive to decode? I am hoping for transparent (as LAME -APS is to WAV). I realize their would be some loss, but as long as its not percievable then Im ok if there is significant space savings to be had.

[nm]

XviD is probably better for that, if you want to preserve film grain too.

[Morte66]

I do full resolution (720x576 PAL) backups in constant quality mode with quality set to "22" on x264's scale. I like deblocking (-1,-1) which smooths things a little, but if you want to look like the original go for (-2,-2). You'll have trouble telling original from copy at a normal viewing distance. I spent days of mucking about to arrive at this, and I decided at the start that if I was going to sit through a slow encoder like x264 I wasn't going to accept inferior results. :)

In constant quality mode, the settings (number of reference frames etc) trade compression vs speed. I generally run some noise filtering before the encode and I use slow but not silly settings in x264. That gets me an average of average of, oh, 300MB for a ~42 minute TV episode (which was maybe 1.7GB on DVD). It runs at 2.5 to 3 fps on an Athlon XP 1900+.

That's 720x576 -- in Xvid i'd expect to resize down to 640x480 or 720x400 for similar quality and size. OTOH Xvid would be twice as fast.

Xvid really scores when you trade some size for speed and run it single pass at "quantizer 2", which will drop the file size by about half (with a huge variation). At that setting, it's pretty much perfect and there's no real advantage to dual pass or advanced settings (which there would be with higher compression). And it's fast -- about three times as fast as x264, as fast as MPEG2 encoders like Quenc and HC.

[berrinam]

XviD is probably better for that, if you want to preserve film grain too.
Sharktooth's EQM matrix is good for grain preservation in AVC.

[TheResonator]

With commercial encoders, we found grainy 1080p 24fps film sequences were coded "transparently" in 8 mbps High Profile (8x8 DCT) with film grain synthesis (FGS) versus 12 mbps with with Main Profile.

The perk of AVC is that it will be around for a long time thanks to Blu-Ray / HD-DVD. You will soon be able to drop your .mp4 files into a DVD authoring tool and burn a disc (red laser or blue) that will play on any high def DVD player. I don't think that compatibility will exist in 10 years for XVID content.
(God knows what kind of crazy parametric coders will be emerging by then).

[gnutellafan]

The perk of AVC is that it will be around for a long time thanks to Blu-Ray / HD-DVD. You will soon be able to drop your .mp4 files into a DVD authoring tool and burn a disc (red laser or blue) that will play on any high def DVD player. I don't think that compatibility will exist in 10 years for XVID content.
(God knows what kind of crazy parametric coders will be emerging by then).

Exactly, which is why I am considering transcoding to AVC. I still have not found an easy way to do so and want to be sure that when I can afford a nice big screen that the picture will be the same as the original DVD.

[check]

The level for a transperant encode is probably around --crf 18 to 22, with deblocking from -2,-2 to 0,0 (for reference, the deblocking numbers work like ogg q presets do, 0,0 does not mean "no filtering", just "less than 1,1" and "more than -1,-1). Personally I use --crf 22 and deblocking -1,-2. Of course, if you ever intend to transcode the files again, I would go down to --crf 18

TheResonator covered future compatibility pretty well, and add to that ffdshow is open source, available on linux and you have a pretty good lifespan for the files.

(ps, last file I tried with lossless came out around 20-30mbits, but can't remember if the file was animated or live action. Regardless, yes, a true lossless encode will work out far bigger :))

[Avish]

When can I safely turn off the deblocking filter? [eg. If my source is blockless]:)
& does disabling it fastens encoding a bit?

[bond]

deblocking is not for deblocking blocky sources, but for avoiding blocks created by the encoding process. best would be if you try yourself whether turning off deblocking is ok for your qualitywise

disabling deblocking makes encoding and decoding faster (for how much check my decoder comparison sticky)