[FFmpeg-devel] [PATCH 3/7] avfilter/vf_framerate: factorize blend_frames

[Marton Balint]

On Wed, 3 Jan 2018, Marton Balint wrote:

>
> On Tue, 2 Jan 2018, Michael Niedermayer wrote:
>
>> On Sun, Dec 10, 2017 at 11:11:18PM +0100, Marton Balint wrote:
>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>>> ---
>>>  libavfilter/vf_framerate.c | 54 
> ++++++----------------------------------------
>>>  1 file changed, 7 insertions(+), 47 deletions(-)
>>
>> This broke fate-filter-framerate-up on x86-32 (gcc 4.8 (Ubuntu 
> 4.8.5-2ubuntu1~14.04.1))
>>
>> --- tests/ref/fate/filter-framerate-up	2017-12-31 19:27:30.039451874 
> +0100
>> +++ tests/data/fate/filter-framerate-up	2018-01-02 02:12:56.151674862 
> +0100
>> @@ -4,12 +4,12 @@
>> #dimensions 0: 320x240
>> #sar 0: 1/1
>> 0,          0,          0,        1,   115200, 0x3744b3ed
>> -0,          1,          1,        1,   115200, 0xc44bdc65
>> -0,          2,          2,        1,   115200, 0xa17f0d74
>> -0,          3,          3,        1,   115200, 0xb0c83274
>> -0,          4,          4,        1,   115200, 0x232d6368
>> +0,          1,          1,        1,   115200, 0x3744b3ed
>> +0,          2,          2,        1,   115200, 0x3744b3ed
>> +0,          3,          3,        1,   115200, 0x3744b3ed
>> +0,          4,          4,        1,   115200, 0x6e318ba0
>> 0,          5,          5,        1,   115200, 0x6e318ba0
>> -0,          6,          6,        1,   115200, 0x247e846e
>> -0,          7,          7,        1,   115200, 0x89e27599
>> -0,          8,          8,        1,   115200, 0x31c5704e
>> -0,          9,          9,        1,   115200, 0x97e45fec
>> +0,          6,          6,        1,   115200, 0x6e318ba0
>> +0,          7,          7,        1,   115200, 0x6e318ba0
>> +0,          8,          8,        1,   115200, 0x6e318ba0
>> +0,          9,          9,        1,   115200, 0x48d65876
>> Test filter-framerate-up failed. Look at 
> tests/data/fate/filter-framerate-up.err for details.
>> make: *** [fate-filter-framerate-up] Error 1
>>
>> in master the diff now looks like this:
>> --- tests/ref/fate/filter-framerate-up	2017-12-31 19:27:30.039451874 
> +0100
>> +++ tests/data/fate/filter-framerate-up	2018-01-02 02:42:46.103712572 
> +0100
>> @@ -4,12 +4,12 @@
>> #dimensions 0: 320x240
>> #sar 0: 1/1
>> 0,          0,          0,        1,   115200, 0x3744b3ed
>> -0,          1,          1,        1,   115200, 0xc44bdc65
>> +0,          1,          1,        1,   115200, 0x3744b3ed
>> 0,          2,          2,        1,   115200, 0xa17f0d74
>> 0,          3,          3,        1,   115200, 0xb0c83274
>> 0,          4,          4,        1,   115200, 0x232d6368
>> 0,          5,          5,        1,   115200, 0x6e318ba0
>> -0,          6,          6,        1,   115200, 0x247e846e
>> +0,          6,          6,        1,   115200, 0x6e318ba0
>> 0,          7,          7,        1,   115200, 0x89e27599
>> 0,          8,          8,        1,   115200, 0x31c5704e
>> 0,          9,          9,        1,   115200, 0x97e45fec
>> Test filter-framerate-up failed. Look at 
> tests/data/fate/filter-framerate-up.err for details.
>> make: *** [fate-filter-framerate-up] Error 1
>
> Does not happen if compiled with -O1 or -O0. With -O2 and -O3 
> fabsf(intepolate) becomes NaN.
>
> I am guessing that some floating point state is lost because of the SAD 
> MMX instructions, but I don't know if this is a compiler bug or something 
> should be done differently.
>
> Do you have an idea how to proceeed?

I guess I will just commit the patch which eliminates the floating 
point calculations, that should fix this failure as well.

Regards,
Marton