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View Full Version : Relaible HD .ty to "standard" (SD) DVD?



wbelhaven
03-04-2006, 04:45 AM
Hi,

I'm looking for a way to take HD programs extracted from my HR10-250 and transcode them to "standard DVD" that will play on a "standard" DVD player. I'm close, but not yet there. Here's what I'm doing:

Use TyTool or mfs_ftp to extract a .ty
Use TyTool's GOP editor to generate key files and trim the crud (before/after stuff, commercials, etc.)
Use TyTool to generate an "HD" MPG.
Use mencoder to transcode to SD "DVD compliant" MPG.
Use dvdauthor to create the DVD "filesystem".
Use RecordNow to burn the DVD-R.

The problem is that the resultant DVD will play fine on a computer, but when it's burned to DVD-R, it sometimes causes the DVD player to freeze, stutter, or otherwise playback the video in a rather unpleasant fashion.

NOTE: I'm almost certain this is not a physical (media) problem, because every DVD that I've DVD Decyrpt'ed, DVD Shrink'ed <grin>, and DVD Burn'ed (to DVD-R) has worked perfectly on my DVD player -- never any freezes, stutters, or otherwise, unlike the ones I've created using the process enumerated above (HD to SD DVD).

I suspect the problem is in my mencoder settings. The audio in this particular file was already 384kbps AC3 (DD 5.1), which was just fine for me. Here's the mencoder command line I'm using:


mencoder -delay 0.1 -oac copy -ovc lavc -of mpeg -mpegopts format=dvd \
-vf crop=1254:1066,scale=720:480,harddup -lavcopts \
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=6000:vbitrate=3734:keyint=18:aspect=16/9 \
-ofps 30000/1001 -o output.mpg input.mpg

The DVD player might be freezing because the max bitrate is being exceeded. (My DVD player has the ability to display the instantaneous bitrate while playing, as do several of the software DVD players I'm testing with.) For grins, I did a test where I changed vrc_maxrate from 6000 to 9000 and the resultant MPG file was bit for bit identical in the two cases (at least accoding to diff). Is there some non-obvious magic to using vrc_maxrate that I need to know about?

Another thing I've noticed is that the resultant video looks very "film like" instead of "video like", even though the source material was a live, video sporting event (1080i). I've also noticed that when adding the ":1" option to the scale filter (i.e., scale:720:480:1), which theoretically means "interlaced-aware scaling", that mencoder crashes before finishing the job.

Hopefully that's enough background and speculation to be useful. Has anyone figured out a 100% reliable set of options to include on mencoder to transcode HD .ty files into "DVD compliant" .mpg, that will actually play on a multitude of "standard" DVD players?

Thanks,
Walter

wbelhaven
03-05-2006, 02:11 PM
Whoa, slow down, don't everyone shout at once. :)

Ok, perhaps I need to focus a bit on one particular aspect of my question. Why does the transcoded video always look "film like" even when the source is "live video"? I'm going 1080i to 480i, same frame/field rate before & after, but the video when played back on the DVD player just looks like film. (I've tried S-video out, Component Interlaced out, and Component Progressive out, and they all have that same film-like look.) Is that because the bitrate is so low? -- the original 1080i is roughly 14Mbps, the transcoded 480i is roughly 4Mbps, though I've also tried higher bitrates and had the same result. It seems as if there's a de-interlacing then re-interlacing going on, which I suppose could help motion estimation and whatnot, but it could potentially be wasteful and destructive.

If I need to bug off to an mencode forum or something, please let me know. I figure I'm not the first person to experience this with HD extraced from an HR10-250, though, and would like to know if someone has already figured this out.

WB

wbelhaven
03-06-2006, 08:54 PM
On the off chance that anyone's actually listening :p , I've got some progress to report. In order to retain the "video" appearance of the original 1080i video source, and in the process vastly improve the fluidity of motion in the resulting transcoded video, I need to tell mencoder, and specifically, lavc, all of the following:

Use interlace-aware scaling: scale=720:480:1
Use interlace-aware DCT: :ildct
Use interlace-aware motion estimation: :ilme
Render "top-field first": :top=0

Putting that all together, here's the command line I'm now using:


mencoder -delay 0.35 -oac copy -ovc lavc -of mpeg -mpegopts format=dvd
-vf crop=1254:1066,scale=720:480:1,harddup -lavcopts
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9696:vbitrate=5731:keyint=18:aspect=16/9:ildct:ilme:top=0
-ofps 30000/1001 -o output.mpg input.mpg
The -delay syncs up the audio, and the crop removes the icky overscan crud. The vbitrate is chosen to make the entire program fit on a single-layer DVD-R, and the vrc_maxrate insures that the video plus audio does not exceed the DVD standard's maximum overall bitrate.

So far this plays swimmingly well on my Sony "set top" DVD player. I still have a freeze on my Panasonic DVD-XP30, the cause of which I'm still trying to isolate. It seems to happen just after a cut I made with the TyTool key editor to remove a set of commercials. Hmmmmm.

Anyway, hope this helps someone other than me. ::D

WB

MemphisBrian72
03-06-2006, 09:49 PM
I did an experiment along these same lines. Never got as detailed with the tweaking, but this (very long) process worked for me on an episode of Lost:

1. Tytool 10r1 -> .Ty file (6.5 GB) -> Key/cut -> VOB Mplex -> .VOB file (4.5 GB)
2. Change the extension of the large 4GB .VOB to .MPG, add it as new movie to Roxio MyDvd menu
3. I set the preferences in Roxio to Widescreen, prog scan, high quality, not sure if it made a difference...
4. Burn DVD - Roxio re-encoded to a 2.92 GB file...

There is also a utility called hdemux you can find on the forums. Using this in conjunction with TyToolr10 let me create a large MPG file that was watchable on a laptop with Windows Media player.

Using both HD and SD DirecTivos and a DVD player I then played the recordings and did an A/B comparison. The "downsampled" DVD looked great on a standard-def TV but lousy on an HD one.

94SupraTT
03-06-2006, 10:28 PM
There is also a utility called hdemux you can find on the forums. Using this in conjunction with TyToolr10 let me create a large MPG file that was watchable on a laptop with Windows Media player.


Interesting.

5speed
03-09-2006, 06:04 PM
Hey, thanks for sharing! I'd been searching like crazy for a way to do this and hadn't found anything useful. Sorry you didn't get any help - but you sure helped me! Going off now to download mencoder and start experimenting.