[FFmpeg-user] Bit Depth of PNG Overlay with Alpha channel

[Paul B Mahol]

On 11/26/17, Flatgrey <pete at flatgrey.com> wrote:
> Thanks Gyan
>
> That improved things slightly.  The difference is pretty noticeable though
> to the output I can get with Premiere.
>
> Do you know if you can specify the colour bit depth for the png file?

png supports 8 bit depth or 16 bit depth per pixel component.
If you want more than 8 bit depth use maskedmerge filter to overlay
with 16 bit depth.

And I think you want unpremultiply filter, as currently overlay filter
only knows about straight.

>
> Thanks
>
> Pete
>
> Sent from my iPhone
>
>> On 25 Nov 2017, at 11:57, Gyan Doshi <gyandoshi at gmail.com> wrote:
>>
>>
>>> On 11/25/2017 3:20 PM, Pete Willis wrote:
>>> We have a transparent PNG file with a drop shadow. The drop shadow when
>>> overlayed onto a Mov is rendering very dark.
>>
>> This is usually related to whether the input color pixels are straight or
>> pre-multiplied.
>>
>> Try
>>
>>    ffmpeg -I TEST-1.mxf -i test-1.png -filter_complex
>> '[1]premultiply=inplace=1[img];[0][img]overlay' -c:v libx264  -profile
>> high10 -map '[out]' out2.mp4
>>
>>
>> Regards,
>> Gyan
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