[FFmpeg-devel] [PATCH 1/2 v3] avfilter: add readvitc filter

Tobias Rapp t.rapp at noa-archive.com
Fri Apr 8 15:24:56 CEST 2016

On 08.04.2016 14:54, Paul B Mahol wrote:
> On 4/8/16, Tobias Rapp <t.rapp at noa-archive.com> wrote:
>> On 08.04.2016 12:48, Carl Eugen Hoyos wrote:
>>> Tobias Rapp <t.rapp <at> noa-archive.com> writes:
>>>>> AV_PIX_FMT_YUV440P? Also J variants...
>>>> Good catch, I was lazy and just copied the function from vf_eq.c. The
>>>> updated patch should contain all pixel formats with planar 8bit luma
>>>> component.
>>> Instead of listing the formats, check for pix_fmts
>>> that are 8bit and planar.
>> That might be an even better idea. Working on v3 of the patch I noticed
>> that YA8 (which was on the list of v2) is not planar, but NV12 and NV21
>> (which were missing in v2) have a planar Y.
>> Have attached version 3 of the patch which:
>> - filters the list of all pixel formats dynamically
>> - supports thr_b and thr_w parameters having the same value
>> - updates the warning if thr_b == thr_w to print the parameter value
>> instead of the internal 8-bit value
>> - has reduced number of parentheses in CRC code
>> Regards,
>> Tobias
> Now, when someone adds 8bit X planar format which is not YUV it will break.

It depends on whether the equation "is_yuv_or_gray = (desc->flags & 
AV_PIX_FMT_FLAG_RGB) == 0)" can be made or not. The comment in 
libavutil/pixdesc.h made me assume it is safe to do so:

  * The pixel format contains RGB-like data (as opposed to YUV/grayscale).
#define AV_PIX_FMT_FLAG_RGB          (1 << 5)

So what has more weight, the aspect of defensive programming or the cost 
of maintaining a static list?


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