[FFmpeg-devel] [PATCH] Add DPX decoder rev-18

[Jimmy Christensen]

On 2009-06-04 00:34, Michael Niedermayer wrote:
> On Wed, Jun 03, 2009 at 08:52:42PM +0200, Jimmy Christensen wrote:
>> On 2009-06-03 20:20, Reimar D?ffinger wrote:
>>> Hm. I really wonder which compiler you use.
>>> Anyway I guess Michael would accept a version using macros if it was
>>> done without adding useless calculation.
>>> Except that it's rather silly to use macros in cases like this when
>>> there is absolutely no reason to.
>>> Example:
>>> static inline unsigned make_16bit(unsigned value)
>>> {
>>>       // mask away invalid bits
>>>       value&= 0xFFC0;
>>>       // correctly expand to 16 bits
>>>       return value + (value>>   10);
>>> }
>>>
>>>               *dst++ = make_16bit(rgbBuffer>>   16);
>>>               *dst++ = make_16bit(rgbBuffer>>    6);
>>>               *dst++ = make_16bit(rgbBuffer<<    4);
>>
>> Thanks for the code. Works perfectly and keeps it's speed. I'm using gcc
>> 4.3.3 on Ubuntu 9.04 amd64. C is not exactly my biggest force and
>> appreciate any help I can get.
>>
>> Btw. should I also upload sample images to test with?
>
> hmm, dont we already have pngs somewhere ...
> anyway, uploading more surely doesnt hurt ...

pngs? This is a decoder for dpx files :) Have uploaded some samples to 
the samples.mplayerhq.hu ftp. Both 10bit and 16bit samples.

>
>
> [...]
>> +static int decode_frame(AVCodecContext *avctx,
>> +                        void *data,
>> +                        int *data_size,
>> +                        AVPacket *avpkt)
>> +{
>> +
>
>> +    const uint8_t *headerBuffer = avpkt->data;
>> +    const uint8_t *buf          = avpkt->data;
>
> redundant
>

It was to make jumping from the start of the file to the offset easier. 
Found another way to do it instead.

> [...]
>> +
>
>> +    avctx->width  = w;
>> +    avctx->height = h;
> [...]
>> +    if (w != avctx->width || h != avctx->height)
>> +        avcodec_set_dimensions(avctx, w, h);
>
> this wont work in that order
>

Removed those 2 lines, as they did seem kinda rendundant aswell.

Added support for 16-bit dpx files aswell. I know the code looks 
redundant, but I didn't want to make a if or switch case for each pixel. 
With the switch case inside the for loops it took a performance hit of 
about 6-7% of total encode time which I found a little unacceptable. 
Also the 10bit files needs to first go into a temporary buffer for the 
color information to get extracted. With 16-bit files it's not necessary 
so that path should also be a little faster. Haven't tested encodes with 
16-bit sequences, only single files.

Removed the version variable since it wasn't used anyway.
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