[FFmpeg-devel] [PATCH] Add FITS Encoder

[Carl Eugen Hoyos]

2017-07-21 20:16 GMT+02:00 Reimar Döffinger <Reimar.Doeffinger at gmx.de>:
> On 21.07.2017, at 16:26, Paras Chadha <paraschadha18 at gmail.com> wrote:
>
>> On Fri, Jul 21, 2017 at 3:27 AM, Carl Eugen Hoyos <ceffmpeg at gmail.com>
>> wrote:
>>
>>> 2017-07-20 21:46 GMT+02:00 Paras Chadha <paraschadha18 at gmail.com>:
>>>
>>>> +            case AV_PIX_FMT_RGB24:
>>>> +            case AV_PIX_FMT_RGBA:
>>>> +                for (k = 0; k < naxis3; k++) {
>>>> +                    for (i = 0; i < avctx->height; i++) {
>>>> +                        ptr = p->data[0] + (avctx->height - i - 1) *
>>> p->linesize[0] + k;
>>>> +                        for (j = 0; j < avctx->width; j++) {
>>>> +                            bytestream_put_byte(&bytestream, ptr[0]);
>>>> +                            ptr += naxis3;
>>>
>>> (Sorry if this is nonsense:)
>>> Shouldn't you be using PIX_FMT_GBRP and PIX_FMT_GBRAP?
>>>
>>
>> No, the current pixel formats are working fine. I have tested using GIMP
>> too. It is showing all the RGB images (and others too) correctly.
>
> I think that's not what he meant.
> You are explicitly requesting a packed format that has the data in
> RGBRGBRGB... order, and you then need these loops to split it into
> RRRR... GGGG... BBBB...
> He's suggesting you should simply request the format storing the data like that

Yes, this makes above code both simpler and (on typical hardware)
always faster (it will never be slower, no matter the hardware).

> then all you need to do is the unsigned -> signed conversion

Which is not necessary for the above case.

Carl Eugen