8bps.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

/*
 * Quicktime Planar RGB (8BPS) Video Decoder
 * Copyright (C) 2003 Roberto Togni
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

/**
 * @file 8bps.c
 * QT 8BPS Video Decoder by Roberto Togni <rtogni at bresciaonline dot it>
 * For more information about the 8BPS format, visit:
 *   http://www.pcisys.net/~melanson/codecs/
 *
 * Supports: PAL8 (RGB 8bpp, paletted)
 *         : BGR24 (RGB 24bpp) (can also output it as RGBA32)
 *         : RGBA32 (RGB 32bpp, 4th plane is probably alpha and it's ignored)
 *
 */

#include <stdio.h>
#include <stdlib.h>

#include "common.h"
#include "avcodec.h"


const enum PixelFormat pixfmt_rgb24[] = {PIX_FMT_BGR24, PIX_FMT_RGBA32, -1};

/*
 * Decoder context
 */
typedef struct EightBpsContext {

	AVCodecContext *avctx;
	AVFrame pic;

	unsigned char planes;
	unsigned char planemap[4];
} EightBpsContext;


/*
 *
 * Decode a frame
 *
 */
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
	EightBpsContext * const c = (EightBpsContext *)avctx->priv_data;
	unsigned char *encoded = (unsigned char *)buf;
	unsigned char *pixptr;
	unsigned int height = avctx->height; // Real image height
	unsigned int dlen, p, row;
	unsigned char *lp, *dp;
	unsigned char count;
	unsigned int px_inc;
	unsigned int planes = c->planes;
	unsigned char *planemap = c->planemap;
  
  
	/* no supplementary picture */
	if (buf_size == 0)
		return 0;

	if(c->pic.data[0])
		avctx->release_buffer(avctx, &c->pic);

	c->pic.reference = 0;
	c->pic.buffer_hints = FF_BUFFER_HINTS_VALID;
	if(avctx->get_buffer(avctx, &c->pic) < 0){
		av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
		return -1;
	}

	/* Set data pointer after line lengths */
	dp = encoded + planes * (height << 1);

	/* Ignore alpha plane, don't know what to do with it */
	if (planes == 4)
		planes--;

	px_inc = planes + (avctx->pix_fmt == PIX_FMT_RGBA32);

	for (p = 0; p < planes; p++) {
		/* Lines length pointer for this plane */
		lp = encoded + p * (height << 1);

		/* Decode a plane */
		for(row = 0; row < height; row++) {
			pixptr = c->pic.data[0] + row * c->pic.linesize[0] + planemap[p];
			dlen = be2me_16(*(unsigned short *)(lp+row*2));
			/* Decode a row of this plane */
			while(dlen > 0) {
				if ((count = *dp++) <= 127) {
					count++;
					dlen -= count + 1;
					while(count--) {
						*pixptr = *dp++;
						pixptr += px_inc;
					}
				} else {
					count = 257 - count;
					while(count--) {
						*pixptr = *dp;
						pixptr += px_inc;
					}
					dp++;
					dlen -= 2;
				}
			}
		}
	}

	if (avctx->palctrl) {
		memcpy (c->pic.data[1], avctx->palctrl->palette, AVPALETTE_SIZE);
		if (avctx->palctrl->palette_changed) {
			c->pic.palette_has_changed = 1;
			avctx->palctrl->palette_changed = 0;
		} else
			c->pic.palette_has_changed = 0;
	}

	*data_size = sizeof(AVFrame);
	*(AVFrame*)data = c->pic;

	/* always report that the buffer was completely consumed */
	return buf_size;
}


/*
 *
 * Init 8BPS decoder
 *
 */
static int decode_init(AVCodecContext *avctx)
{
	EightBpsContext * const c = (EightBpsContext *)avctx->priv_data;

	c->avctx = avctx;
	avctx->has_b_frames = 0;

	c->pic.data[0] = NULL;

	switch (avctx->bits_per_sample) {
		case 8:
			avctx->pix_fmt = PIX_FMT_PAL8;
			c->planes = 1;
			c->planemap[0] = 0; // 1st plane is palette indexes
			if (avctx->palctrl == NULL) {
				av_log(avctx, AV_LOG_ERROR, "Error: PAL8 format but no palette from demuxer.\n");
				return -1;
			}
			break;
		case 24:
			avctx->pix_fmt = avctx->get_format(avctx, pixfmt_rgb24);
			c->planes = 3;
			c->planemap[0] = 2; // 1st plane is red
			c->planemap[1] = 1; // 2nd plane is green
			c->planemap[2] = 0; // 3rd plane is blue
			break;
		case 32:
			avctx->pix_fmt = PIX_FMT_RGBA32;
			c->planes = 4;
#ifdef WORDS_BIGENDIAN
			c->planemap[0] = 1; // 1st plane is red
			c->planemap[1] = 2; // 2nd plane is green
			c->planemap[2] = 3; // 3rd plane is blue
			c->planemap[3] = 0; // 4th plane is alpha???
#else
			c->planemap[0] = 2; // 1st plane is red
			c->planemap[1] = 1; // 2nd plane is green
			c->planemap[2] = 0; // 3rd plane is blue
			c->planemap[3] = 3; // 4th plane is alpha???
#endif
			break;
		default:
			av_log(avctx, AV_LOG_ERROR, "Error: Unsupported color depth: %u.\n", avctx->bits_per_sample);
			return -1;
	}

  return 0;
}




/*
 *
 * Uninit 8BPS decoder
 *
 */
static int decode_end(AVCodecContext *avctx)
{
	EightBpsContext * const c = (EightBpsContext *)avctx->priv_data;

	if (c->pic.data[0])
		avctx->release_buffer(avctx, &c->pic);

	return 0;
}



AVCodec eightbps_decoder = {
	"8bps",
	CODEC_TYPE_VIDEO,
	CODEC_ID_8BPS,
	sizeof(EightBpsContext),
	decode_init,
	NULL,
	decode_end,
	decode_frame,
	CODEC_CAP_DR1,
};