[FFmpeg-devel] evaluating the experimental status of ffv1 version 3

Peter B. pb at das-werkstatt.com
Fri Sep 7 15:34:54 CEST 2012

On 09/06/2012 06:01 PM, Michael Niedermayer wrote:
> On Thu, Sep 06, 2012 at 09:35:44AM +0200, Peter B. wrote:
>> 1) Run the whole test-suite under clean conditions with different
>> input material (VHS, DigiBeta, ...). All tests done so far were
>> fine, but I've done them with 1 single source video, and while
>> developing my testscript. So I wouldn't guarantee for what I saw.
> also see http://media.xiph.org/video/derf/ for more test material
I've already used that source before. Unfortunately, they only have
HD-content with 422 subsampling max. However, they're good test-videos
as their license is cleared.

>> 2) The strange fact that newer versions of ffmpeg produce larger
>> FFv1 AVIs - even with FFv1.1
> did you report this previously? did we come up with some conclusion?
> if not which revission is small and which large ?

Yeah, I posted it on the mailing list (on June 3rd, 2012 - 02:28pm) and
Roger Pack replied that I should try compiling the ffmpeg version,
ffdshow-tryouts was built with (as I used it to create those files) and
see what filesize it produces. Then it could be possible to compare that
revision with the current head to spot the reason.

I haven't found the time yet, to fetch and compile the old version :(
Still TODO ;)

>> @Michael:
>> What's your opinion? Are there any parts in the code/bitstream which
>> you think should be examined more closely by testing?
> the effects of gop size (especially gop=1) and slice count on the
> compression rate (especially with 2pass mode)
Roger that.
About the 2pass mode: You said I could create a pass logfile from one
video and use that one to encoder a completely different video, right?
Could you please provide me a commandline example of how you do that?
Because when I tried, it would only accept the pass logfile from the
*same* video.


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