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beandog
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Joined: 04 May 2003
Posts: 2014
Location: /usa/utah

PostPosted: Mon Feb 17, 2014 6:48 pm    Post subject: Reply with quote

Nicias wrote:
Maybe, I mostly do movies. The other stuff I've had is relatively fine. I mean it is often telecined, either 23 or 23223 (or somesuch for PAL->NTSC) and yeah, 30=30000/1001.


I so envy PAL. 25 fps. No mess. *sigh*
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dobbs
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Joined: 20 Aug 2005
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PostPosted: Mon Feb 17, 2014 7:54 pm    Post subject: Reply with quote

beandog wrote:
My *biggest* use for it was always to do a rawcopy of the stream. There's still not a really *good* app that will just let you select the video title, the audio streams and the subtitles and just do a raw dump of it, so mencoder fits the bill nicely.

I use ffmpeg for that (-vcodec copy -acodec copy). You can see an example commented in my script, though it encodes audio instead of copying. The trick is to figure out the stream mapping, which may or may not fit your "really good" requirement. ;) On the whole though, I gravitate towards Mencoder for video processing (filters) and ffmpeg for muxing. Looks like a lot of work is going into ffmpeg's filters right now, so I may migrate to that if it starts working for my needs.

beandog wrote:
If you're interested, I'll dig through my code and see what wrapper I came up with for HandBrake. It really does some great stuff.

Please!

beandog wrote:
Also, just coming back to Gentoo multimedia and looking over the forums, I'm noticing that nobody uses it or even knows about it. Makes me think that perhaps some good solid mid-user-level documentation could come in handy, do a fair assessment of pros vs cons of other DVD ripper apps.

I will always support mid-level documentation! The links in your signature are impressive.

beandog wrote:
dobbs wrote:
I just wish I understood the motives behind the encoding.

Generally interlacing is done to save space. Makes sense on something like TNG where you have four hours on one DVD with multiple audio tracks (English Dolby 5.1, English Dolby stero, etc.).

I dunno if that holds for digital encodings. I think interlacing was introduced to compensate for old television tube refresh rates and possibly trying desperately to get a decent resolution+frame rate out of limited broadcast bandwidth. Not entirely clear on the history there. But I'm more confused about mixed telecining of progressive content in DVDs. You end up with more fields in the same time period vs. progressive encoding. And I'm not convinced the telecining process isn't done after encoding, where fields are just copied verbatim. If that's true, you're only padding the stream with redundant bits. The bright side would be that it's computationally trivial to reverse. I really need a tool to inspect the MPEG data structures directly (extract individual packets and video fields).

beandog wrote:
I so envy PAL. 25 fps. No mess. *sigh*

Higher vertical resolution and better color handling as well.

OT: Why is my U.S. English dictionary marking "color" as spelled incorrectly?
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beandog
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Joined: 04 May 2003
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PostPosted: Mon Feb 17, 2014 9:16 pm    Post subject: Reply with quote

dobbs wrote:
beandog wrote:
My *biggest* use for it was always to do a rawcopy of the stream. There's still not a really *good* app that will just let you select the video title, the audio streams and the subtitles and just do a raw dump of it, so mencoder fits the bill nicely.

I use ffmpeg for that (-vcodec copy -acodec copy). You can see an example commented in my script, though it encodes audio instead of copying. The trick is to figure out the stream mapping, which may or may not fit your "really good" requirement. ;) On the whole though, I gravitate towards Mencoder for video processing (filters) and ffmpeg for muxing. Looks like a lot of work is going into ffmpeg's filters right now, so I may migrate to that if it starts working for my needs.


I should have clarified ... there's not really anything to read directly from the *DVD structure* (so, using libdvdread) to do a complete dump. Unless ffmpeg added libdvdread support and I totally missed it...

dobbs wrote:
beandog wrote:
If you're interested, I'll dig through my code and see what wrapper I came up with for HandBrake. It really does some great stuff.

Please!


Okay I threw up my entire DVD app on github ... this could be a good case of "makes sense to me and no one else" though. :T Here's my handbrake class which you'd probably have to dig through to have it make sense of anything ... I guess a proper HandBrake CLI wrapper script would actually be in order. That could come in useful. Sort of a simple wrap-around to make common situations pretty simple. :)

Actually this code might make more sense, if for no other reason than you can easily see the logic I'm running through.

dobbs wrote:
beandog wrote:
Also, just coming back to Gentoo multimedia and looking over the forums, I'm noticing that nobody uses it or even knows about it. Makes me think that perhaps some good solid mid-user-level documentation could come in handy, do a fair assessment of pros vs cons of other DVD ripper apps.

I will always support mid-level documentation! The links in your signature are impressive.


Ah, thanks man, I've decided to just focus my multimedia efforts on DVDs from now on. I've recently started learning C (hence the other repo) and that's what's making fixing some of these bugs possible, and writing my own to workaround other stuff. It's gotten me wanting to work on multimedia again, so I'm reviving the old DVDs wiki and going to work on putting some actual helpful content on there (fex, the HandBrake doc).

dobbs wrote:
I really need a tool to inspect the MPEG data structures directly (extract individual packets and video fields).


Okay I am *sure* that there is something out there that will do that. I've seen a ton of Linux DVD apps, and I know that's possible, but I don't know where you'd find it ... Hmm. Lemme look around.

Here's a github repo that might get you in the right direction. Or not. Also, get the libdvdnav tarball and look through it's examples directory. If none of those help, post to the ffmpeg or libav development mailing lists, and I'm sure they'll be able to point you in the right direction. :)

dobbs wrote:
OT: Why is my U.S. English dictionary marking "color" as spelled incorrectly?


Check your locale? Make sure it's correct. :)
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Nicias
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Joined: 06 Dec 2005
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PostPosted: Sun Apr 13, 2014 3:16 pm    Post subject: Reply with quote

I came across this old thread recently, just wanted to say that the newest point version of ffmpeg in portage (2.2.1) does have the dejudder filter, so you can give it shot without using the git head if you want.
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