[XviD-devel] Questions / Bug fixes / Patches

Carl Eric Codere cecodere at yahoo.ca
Tue Nov 23 04:53:02 CET 2010


Greetings,
          The issue of N-VOPs has been discussed again and again, such as in this thread:

http://forum.doom9.org/archive/index.php/t-111622.html

Would it not be possible to add an option, such as my early patch to not use N-VOPs for compatibility reasons. And yes, it is a bug in most players and codecs out there, and not a bug in Xvid... :)

Best regards,
Carl

--- On Mon, 11/22/10, Carl Eric Codere <cecodere at yahoo.ca> wrote:

> From: Carl Eric Codere <cecodere at yahoo.ca>
> Subject: Re: [XviD-devel] Questions / Bug fixes / Patches
> To: xvid-devel at xvid.org
> Received: Monday, November 22, 2010, 10:30 PM
> Greetings,
>         I once again reproduced the
> problem with the frame drop ratio. I 
> did as follows with the following mencoder options:
> 
> -xvidencopts pass=1
> bitrate=768
> me_quality=6
> trellis
> vhq=1:min_iquant=2
> min_pquant=2
> min_bquant=2
> frame_drop_ratio=0
> nopacked
> par=vga11
> profile=sp4a
> 
> Same thing for pass 2. When converted to a MP4 file using
> Mp4Box with the following options:
> ..\tools\mp4box\mp4box -fps %fps%  -nodrop -new -add
> %2_%bitRateHigh%_MP4 at SP_Xvid.avi
> %2_MP4 at SP_%bitRateHigh%_Xvid.mp4
> 
> -> 27 frames are defined as being N-VOP, G-Spot
> specifies them as non packed bitstream N-VOPs. 
> 
> Now, when I use graphedit and replay this video with the
> ffmpeg video decoder and frame grab all these frames, the 27
> frames seem to be missing at constant bitrate. Of course,
> this seems to be a bug with the FFMPEG decoder (which does
> not occur when i use the 3ivx decoder), but the drop ratio
> workaround could possibly solve this problem, as well as
> other numerous compatibility problem, no?
> 
> Best regards,
> Carl
> 
> 
> 
> --- On Mon, 8/30/10, Marcin Jaworski <indrid at o2.pl>
> wrote:
> 
> > From: Marcin Jaworski <indrid at o2.pl>
> > Subject: Re: [XviD-devel] Questions / Bug fixes /
> Patches
> > To: xvid-devel at xvid.org
> > Received: Monday, August 30, 2010, 9:30 AM
> > Quoting Carl Eric Codere:
> > > Greetings,
> > >          But i don't think my
> > patch was applied, should it be applied? Have you
> confirmed
> > that it causes problems in some players or not? On my
> side,
> > I thoughr it would cause problems (I am converting the
> Xvid
> > streams to MP4 streams using mp4box, but it seems
> after
> > testing that i could not reproduce the problem...
> > >
> > > Best regards,
> > > Carl
> > >   
> > It is sufficient to use frame_drop_ratio == -1, that
> will
> > take care of 
> > the "<=" in line 1887 (line 1178 uses the same
> method).
> > 
> > There have been some reports (on Doom9, I think)
> about
> > problems with 
> > N-VOPs (the real ones, not Packed Bitstream) on
> standalone
> > players. But 
> > these were AVI files... If a player is smart enough to
> play
> > MP4 (like 
> > those few players with Nero Digital certification), it
> may
> > be smart 
> > enough to cope with N-VOPs.
> > 
> > Some patches that disable N-VOPs with frame_drop_ratio
> == 0
> > have been 
> > floating around before, but I thought it would be
> better to
> > retain the 
> > original behavior of 0 and use -1 to turn off N-VOPs.
> It
> > seemed 
> > reasonable to keep the official API as it is instead
> of
> > redefining it. I 
> > must admit I haven't tested the behavior of my own
> DVD
> > player with 
> > N-VOPs, but I think users should have the possibility
> of
> > disabling them 
> > if they wish it (flexibility has always been a part of
> the
> > open source 
> > philosophy).
> > 
> > Best regards,
> > Marcin Jaworski
> > _______________________________________________
> > Xvid-devel mailing list
> > Xvid-devel at xvid.org
> > http://list.xvid.org/mailman/listinfo/xvid-devel
> > 
> _______________________________________________
> Xvid-devel mailing list
> Xvid-devel at xvid.org
> http://list.xvid.org/mailman/listinfo/xvid-devel
> 


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