[FFmpeg-devel] [PATCH] bmpenc: support for BGRA

[Paul B Mahol]

On 1/11/12, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Paul B Mahol <onemda <at> gmail.com> writes:
>
>>      switch (avctx->pix_fmt) {
>> +    case PIX_FMT_BGRA:
>> +        avctx->bits_per_coded_sample = 32;
>
> I tested a similar patch and the problem is that ImageMagick does not show
> the
> alpha channel for our encodes, I suspect the reason is we write a too old
> DIB
> header (or another reason).
> If you test, don't use a too old version of ImageMagick, it swaps opaque and
> transparent in the alpha channel.

That's because our encoder create version 3 files instead of version 4.

Version 4 have header size of 108 bytes instead of 40.