[XviD-devel] Questions / Bug fixes / Patches

[Carl Eric Codere]

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
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