[FFmpeg-devel] [PATCH] lavfi: add drawgraph filter

[Paul B Mahol]

On 6/28/15, Dave Rice <dave at dericed.com> wrote:
>
>> On Jun 28, 2015, at 1:54 PM, Paul B Mahol <onemda at gmail.com> wrote:
>>
>> On 6/28/15, Dave Rice <dave at dericed.com> wrote:
>>>
>>>> On Jun 28, 2015, at 11:07 AM, Paul B Mahol <onemda at gmail.com> wrote:
>>>>
>>>> On 6/28/15, Dave Rice <dave at dericed.com> wrote:
>>>>> Hi,
>>>>>
>>>>>> On Jun 27, 2015, at 4:52 PM, Paul B Mahol <onemda at gmail.com> wrote:
>>>>>>
>>>>>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>>>>>> ---
>>>>>> doc/filters.texi           |  76 ++++++++++++
>>>>>> libavfilter/Makefile       |   1 +
>>>>>> libavfilter/allfilters.c   |   1 +
>>>>>> libavfilter/vf_drawgraph.c | 297
>>>>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>>>> 4 files changed, 375 insertions(+)
>>>>>> create mode 100644 libavfilter/vf_drawgraph.c
>>>>>>
>>>>
>>>> [...]
>>>>
>>>>>
>>>>> With this version using a color name for foreground no longer works:
>>>>>
>>>>> This works:
>>>>> ffplay -f lavfi -i mandelbrot -vf
>>>>> signalstats,drawgraph=metadata=lavfi.signalstats.YAVG:min=0:max=255:slide=scroll:bg=green:fg=0x0000FF
>>>>>
>>>>> This doesn't:
>>>>> ffplay -f lavfi -i mandelbrot -vf
>>>>> signalstats,drawgraph=metadata=lavfi.signalstats.YAVG:min=0:max=255:slide=scroll:bg=green:fg=red
>>>>
>>>> AFAIK The expressions can not work with strings.
>>>>
>>>>>
>>>>> Also here's an example with blend:
>>>>> ffplay -f lavfi -i mandelbrot -vf "signalstats,split=3[a][b][c];\
>>>>> [a]drawgraph=metadata=lavfi.signalstats.YAVG:min=0:max=255:slide=scroll:fg=0xFFFF0000:mode=dot[a1];\
>>>>> [b]drawgraph=metadata=lavfi.signalstats.UAVG:min=0:max=255:slide=scroll:fg=0xFF00FF00:mode=dot[b1];\
>>>>> [c]drawgraph=metadata=lavfi.signalstats.VAVG:min=0:max=255:slide=scroll:fg=0xFFFFFF00:mode=dot[c1];\
>>>>> [a1][b1]blend=and[ab];[ab][c1]blend=and[out]"
>>>>>
>>>>
>>>> The blending kills difference in colors so I may add multiple graphs
>>>> support for filter.
>>>
>>> Setting the background to black and blending seems a little better,
>>> though
>>> I'm losing one of my graphs in this example.
>>>
>>> ./ffplay -f lavfi -i mandelbrot -vf "signalstats,split=3[a][b][c];\
>>> [a]drawgraph=lavfi.signalstats.YAVG:min=0:max=255:slide=scroll:bg=black:fg=0x0000FF:mode=dot[a1];\
>>> [b]drawgraph=lavfi.signalstats.YLOW:min=0:max=255:slide=scroll:bg=black:fg=0x00FF00:mode=dot[b1];\
>>> [c]drawgraph=lavfi.signalstats.YHIGH:min=0:max=255:slide=scroll:bg=black:fg=0xFF0000:mode=dot[c1];\
>>> [a1][b1]blend=lighten,[c1]blend=lighten[out]"
>>>
>>> Also the foreground expression is in ABGR or BGR.  This is the opposite
>>> arrangement of what is specified here
>>> http://ffmpeg.org/ffmpeg-utils.html#Color.
>>
>> Using blend for this is SLOW.
>
> If the background could set to full alpha, then multiple graphs could be
> added together with the overlay filter. I tested some alpha expressions with
> bg (black at 00, 0x00000000) and didn't seem to get transparent results.

Because filter use gbrp without alpha as output format. Will change it.
Plan is use RGBA or even YUVA as final output.

>
>> Have you tried new 'line' mode?
>
> Oooo, this is great. Probably more readable than dot in many situations.
>
>> Also expressions allow changing color of dot/line/bar so try it and
>> tell me if its fine.
>
> I tested this with several modes and it works as expected (excepting that
> ABGR/BGR vs RGBA/RGB note). Thanks for adding this.
>
> Some other comments:
> I tried to use an equation within metadata but got no plotted result. For
> instance, "metadata=pow(lavfi.signalstats.YMIN\,2)". There are some values
> that may occur in a wide range, so a logarithmic or mathematically adjusted
> display may be preferable.

Will see what can be done.

>
> Can input width and input height be used in variables within a size
> expression. In many cases I would like to draw the graph over the input
> video, but to do this I must know the input video size in advance.

I do not understand what you want. You want to be able to set size of
filter to input video?

> Dave Rice
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