[FFmpeg-devel] [PATCHv3] add signature filter for MPEG7 video signature

[Dave Rice]

On Jan 6, 2017, at 1:34 PM, Gerion Entrup <gerion.entrup.ffdev at flump.de> wrote:
> 
> On Donnerstag, 5. Januar 2017 02:26:23 CET Michael Niedermayer wrote:
>> On Wed, Jan 04, 2017 at 05:05:41PM +0100, Gerion Entrup wrote:
>>> On Dienstag, 3. Januar 2017 16:58:32 CET Moritz Barsnick wrote:
>>>>>> The English opposite of "fine" is "coarse", not "course". :)
>>>>> Oops.
>>>> 
>>>> You still have a few "courses". (The actual variables, not the types. I
>>>> don't care *too* much, but might be better for consistency.)
>>> You're right. Fixed version attached.
>>> 
>>> 
>>>> From my side - mostly style and docs - it looks fine. Technically, I
>>>> can't judge too much. You went through a long review cycle already, so
>>>> I assume it's fine for those previous reviewers. They have the last
>>>> call anyway.
>>> 
>>> What about FATE? I'm willing to write a test, but don't know the best way. 
>>> There are official conditions, whether the signature is standard compliant. I've 
>>> written a python script to proof that (see previous emails). Nevertheless the 
>>> checks take relatively long and need 3GB inputvideo, so I assume this is not 
>>> usable for FATE.
>> 
>> yes, a 3gb reference is not ok for fate
>> 
>> 
>>> 
>>> One way would be, to take a short input video, take the calculated signature 
>>> and use this as reference, but the standard allow some bitflips and my code
>>> has some of them in comparison to the reference signatures.
>> 
>> then the fate test could/should compare and pass if its within what
>> we expect of our code. (which may be stricter than the reference
>> allowance)
>> there are already tests that do similar for comparing PCM/RAW
> Ok, will try to create a test the next days.
> 
> 
>>> +#define OFFSET(x) offsetof(SignatureContext, x)
>> 
>>> +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
>> 
>> should contin also  AV_OPT_FLAG_FILTERING_PARAM
> Done.
> 
> 
>>> +static int export(AVFilterContext *ctx, StreamContext *sc, int input)
>>> +{
>>> +    SignatureContext* sic = ctx->priv;
>>> +    char filename[1024];
>>> +
>>> +    if (sic->nb_inputs > 1) {
>> 
>>> +        /* error already handled */
>>> +        av_get_frame_filename(filename, sizeof(filename), sic->filename, input);
>> 
>> its more robust to use a av_assert*() on the return code if its assumed
>> to be never failing than just a comment as a comment cannot be
>> automatcially checked for validity currently.
> I chose av_assert0 because the check is done only nb_inputs times.
> 
> The attached patch also fixes the file writing for every frame the one input is
> longer than the other.

Just bumping this thread. I've been using the patch and find it very helpful and would like to see it in libavfilter.
Dave Rice