[FFmpeg-devel] improved DV probe score patch BROKES detecting 1-frame DV

Baptiste Coudurier baptiste.coudurier
Fri Sep 25 20:13:35 CEST 2009

On 09/25/2009 07:01 AM, Michael Niedermayer wrote:
> On Fri, Sep 25, 2009 at 03:15:24PM +0200, Reimar D?ffinger wrote:
>> On Fri, Sep 25, 2009 at 02:43:51PM +0200, Michael Niedermayer wrote:
>>> On Fri, Sep 25, 2009 at 02:18:41PM +0200, Reimar D?ffinger wrote:
>>>> E.g. this change makes it work:
>>>> Index: libavformat/mpeg.c
>>>> ===================================================================
>>>> --- libavformat/mpeg.c  (revision 20013)
>>>> +++ libavformat/mpeg.c  (working copy)
>>>> @@ -78,7 +78,7 @@
>>>>   //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d len:%d\n", sys, priv1,
>>>>   //pspack,vid, audio, p->buf_size);
>>>>       if(sys>invalid&&  sys*9<= pspack*10)
>>>> -        return pspack>  2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
>>>> +        return pspack>  2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4-1; // +1 for .mpg
>>> i would prefer if the scores would not be decreased below 25 to workaround
>>> the inefficiency of the dv probe that we know how to improve.
>> Sorry to be snarky but I would prefer for the MPEG probe function not to
>> grab the world for itself,
> maybe we should test how bad the various<=25 probes are with probetest and
> then consider to reassign scores based on that. If above really is that
> often causing false positives then i surely agree with reducing its score

We can surely continue complicating probing functions, however I believe 
the whole approach should be improved

First taking file extension into account is the first thing to do IMHO.
It seems reasonable to assume that if filename matches and probe is 
sufficiently high enough (this must be defined), this is the correct format.

Also testing all formats is really overkill IMHO, the format matching 
the file extension should be tested first and if it matches, probing 
should be ended.

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