[FFmpeg-devel] [PATCH] Add DPX decoder

[Jimmy Christensen]

Best Regards 
Jimmy Christensen 
Developer 
Ghost A/S 

----- "Michael Niedermayer" <michaelni at gmx.at> wrote:

| On Wed, May 06, 2009 at 01:56:56PM +0100, Jimmy Christensen wrote:
| [...]
| > | 
| > | [...]
| > | > +	if(endian == 0x0) {
| > | > +		offset = AV_RB32(headerBuffer); headerBuffer += 4;
| > | > +		bytestream_get_buffer(&headerBuffer, version, 8);
| headerBuffer +=
| > | 8;
| > | > +		// Jump in extra 744 bytes to end in address 744 + 4 + 4 + 8
| =
| > | 760 = 0x2f8
| > | > +		headerBuffer += 744;
| > | > +		orientation = AV_RB32(headerBuffer); headerBuffer += 4;
| > | > +		w = AV_RB32(headerBuffer); headerBuffer += 4;
| > | > +		h = AV_RB32(headerBuffer); headerBuffer += 4;
| > | > +	} else {
| > | > +		offset = AV_RL32(headerBuffer); headerBuffer += 4;
| > | > +		bytestream_get_buffer(&headerBuffer, version, 8);
| headerBuffer +=
| > | 8;
| > | > +		// Jump in extra 744 bytes to end in address 744 + 4 + 4 + 8
| =
| > | 760 = 0x2f8
| > | > +		headerBuffer += 744;
| > | > +		orientation = AV_RL32(headerBuffer); headerBuffer += 4;
| > | > +		w = AV_RL32(headerBuffer); headerBuffer += 4;
| > | > +		h = AV_RL32(headerBuffer); headerBuffer += 4;
| > | > +	}
| > | 
| > | code duplication
| > | 
| > 
| > No, one is for big endian numbers, the other is for little endian.
| There are 2 types of DPX files.
| 
| you duplicate a flexible endian 32bit reading function
| 

How does it work then?

Sorry, I'm very new to ffmpeg and it's my first patch.

| 
| > 
| > | 
| > | > +
| > | > +	s->width = w;
| > | > +	s->height = h;
| > | > +	s->bpp = 32;
| > | > +	avctx->pix_fmt = PIX_FMT_RGB32;
| > | > +
| > | > +	if(s->picture.data[0])
| > | > +		avctx->release_buffer(avctx, &s->picture);
| > | > +	if(avcodec_check_dimensions(avctx, w, h))
| > | > +		return -1;
| > | > +	if(w != avctx->width || h != avctx->height)
| > | > +		avcodec_set_dimensions(avctx, w, h);
| > | > +	if(avctx->get_buffer(avctx, p) < 0) {
| > | > +		av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
| > | > +		return -1;
| > | > +	}
| > | > +
| > | > +	buf += offset;
| > | > +
| > | > +	ptr = p->data[0];
| > | > +	stride = p->linesize[0];
| > | > +
| > | > +	for(x = 0; x < s->height; x++) {
| > | > +		uint8_t *dst = ptr;
| > | > +		for(y = 0; y < s->width; y++) {
| > | > +			rgbBuffer = AV_RB32(buf);
| > | > +			memcpy(&rgbField, &rgbBuffer, 4);
| > | > +			dst[0] = ((rgbField.R * 256) / 1024);
| > | > +			dst[1] = ((rgbField.G * 256) / 1024);
| > | > +			dst[2] = ((rgbField.B * 256) / 1024);
| > | 
| > | discarding 2 bits in the decoder is unacceptable
| > | also this way of reading is not portable
| > | 
| > 
| > How so? The last 2 bits are not used, since it's too small for alpha
| channel.
| 
| ((rgbField.R * 256) / 1024);
| discards 2 bits
| 

You mean converts from 10bit to 8bit? Yes. But didn't know ffmpeg supported 10bit. Any suggestion on how to get the buffer 10bit is much appreciated.

| [...]
| -- 
| Michael     GnuPG fingerprint:
| 9FF2128B147EF6730BADF133611EC787040B0FAB
| 
| In fact, the RIAA has been known to suggest that students drop out
| of college or go to community college in order to be able to afford
| settlements. -- The RIAA
| 
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