[FFmpeg-devel] FFV1.3

Michael Niedermayer michaelni at gmx.at
Wed Apr 25 13:23:00 CEST 2012

On Tue, Apr 24, 2012 at 09:07:54PM -0400, Dave Rice wrote:
> On Apr 24, 2012, at 8:35 PM, Michael Niedermayer wrote:
> > On Tue, Apr 24, 2012 at 08:05:27PM -0400, Dave Rice wrote:
> >> Hi,
> >> 
> >> On Apr 20, 2012, at 9:50 AM, Michael Niedermayer wrote:
> >> 
> >>> Hi
> >>> 
> >>> Ive just commited some changes to the ffv1 codec v1.3
> >> 
> >> I downloaded from git-master and changed line 900 of ffv1.c to "    s->version=3;" in order to start some testing. So far I haven't gotten any files to encode and have been getting an error on the slice number regarding of the source content. Here's an example output using testsrc as an input.
> > 
> > it need something like -slices 4 
> Thanks that worked. With ffv1 version 1.3 and -slices 4 I'm getting 81 fps encoding whereas version 1.0 on the same content gave 31 fps.
> On my Mac files encoded with ffv1 version 1.3 cause crashes with the latest releases of QuickTime with Perian, VLC, and but works with with ffplay when the version of ffv1.c is set to 0 or to 3.

1.3 support needs latest ffmpeg of course. perian and vlc probably
use a too old version of ffmpegs libavcodec.

> So far with sampling various source content at various bits I've found that both the resulting ffv1 version 1 and version 3 produce the same framemd5s.

also make sure you try 2 pass mode, it compresses better unless the
file is tiny

> In ffv1.c I noticed that a CRC mismatch warning could be given but wasn't able to find a situation to actually produce this warning

per slice CRCs are stored when ec=1
zzuf probably should be able to damage a file to trigger them to be
printed. (havnt tried though)

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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