raw.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。

/*
 * Raw Video Codec
 * Copyright (c) 2001 Fabrice Bellard.
 *
 * 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 raw.c
 * Raw Video Codec
 */
 
#include "avcodec.h"

typedef struct RawVideoContext {
    unsigned char * buffer;  /* block of memory for holding one frame */
    unsigned char * p;       /* current position in buffer */
    int             length;  /* number of bytes in buffer */
    AVFrame pic;             ///< AVCodecContext.coded_frame
} RawVideoContext;

typedef struct PixleFormatTag {
    int pix_fmt;
    unsigned int fourcc;
} PixelFormatTag;

const PixelFormatTag pixelFormatTags[] = {
    { PIX_FMT_YUV420P, MKTAG('I', '4', '2', '0') }, /* Planar formats */
    { PIX_FMT_YUV420P, MKTAG('I', 'Y', 'U', 'V') },
    { PIX_FMT_YUV410P, MKTAG('Y', 'U', 'V', '9') },
    { PIX_FMT_YUV411P, MKTAG('Y', '4', '1', 'B') },
    { PIX_FMT_YUV422P, MKTAG('Y', '4', '2', 'B') },
    { PIX_FMT_GRAY8,   MKTAG('Y', '8', '0', '0') },
    { PIX_FMT_GRAY8,   MKTAG(' ', ' ', 'Y', '8') },


    { PIX_FMT_YUV422,  MKTAG('Y', '4', '2', '2') }, /* Packed formats */
    { PIX_FMT_YUV422,  MKTAG('U', 'Y', 'V', 'Y') },
    { PIX_FMT_GRAY8,   MKTAG('G', 'R', 'E', 'Y') },

    { -1, 0 },
};

static int findPixelFormat(unsigned int fourcc)
{
    const PixelFormatTag * tags = pixelFormatTags;
    while (tags->pix_fmt >= 0) {
        if (tags->fourcc == fourcc)
            return tags->pix_fmt;
        tags++;
    }
    return PIX_FMT_YUV420P;
}

static unsigned int findFourCC(int fmt)
{
    const PixelFormatTag * tags = pixelFormatTags;
    while (tags->pix_fmt >= 0) {
        if (tags->pix_fmt == fmt)
	    return tags->fourcc;
	tags++; 
    }
    return 0;
}

/* RAW Decoder Implementation */

static int raw_init_decoder(AVCodecContext *avctx)
{
    RawVideoContext *context = avctx->priv_data;

    if (avctx->codec_tag)
        avctx->pix_fmt = findPixelFormat(avctx->codec_tag);
    
    context->length = avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
    context->buffer = av_malloc(context->length);
    context->p      = context->buffer;
    context->pic.pict_type = FF_I_TYPE;
    context->pic.key_frame = 1;
    
    avctx->coded_frame= &context->pic;
    
    if (!context->buffer)
        return -1;
   
    return 0;
}

static int raw_decode(AVCodecContext *avctx,
			    void *data, int *data_size,
			    uint8_t *buf, int buf_size)
{
    RawVideoContext *context = avctx->priv_data;
    int bytesNeeded;

    AVPicture * picture = (AVPicture *) data;

    /* Early out without copy if packet size == frame size */
    if (buf_size == context->length  &&  context->p == context->buffer) {
        avpicture_fill(picture, buf, avctx->pix_fmt, avctx->width, avctx->height);
        *data_size = sizeof(AVPicture);
        return buf_size;
    }

    bytesNeeded = context->length - (context->p - context->buffer);
    if (buf_size < bytesNeeded) {
        memcpy(context->p, buf, buf_size);
        context->p += buf_size;
        *data_size = 0;
        return buf_size;
    }

    memcpy(context->p, buf, bytesNeeded);
    context->p = context->buffer;
    avpicture_fill(picture, context->buffer, avctx->pix_fmt, avctx->width, avctx->height);
    *data_size = sizeof(AVPicture);
    return bytesNeeded;
}

static int raw_close_decoder(AVCodecContext *avctx)
{
    RawVideoContext *context = avctx->priv_data;
    
    av_freep(&context->buffer);
    return 0;
}

/* RAW Encoder Implementation */

static int raw_init_encoder(AVCodecContext *avctx)
{
    avctx->coded_frame = (AVFrame *)avctx->priv_data;
    avctx->coded_frame->pict_type = FF_I_TYPE;
    avctx->coded_frame->key_frame = 1;
    avctx->codec_tag = findFourCC(avctx->pix_fmt);
    return 0;
}

static int raw_encode(AVCodecContext *avctx,
			    unsigned char *frame, int buf_size, void *data)
{
    return avpicture_layout((AVPicture *)data, avctx->pix_fmt, avctx->width,
                                               avctx->height, frame, buf_size);
}

AVCodec rawvideo_encoder = {
    "rawvideo",
    CODEC_TYPE_VIDEO,
    CODEC_ID_RAWVIDEO,
    sizeof(AVFrame),
    raw_init_encoder,
    raw_encode,
};

AVCodec rawvideo_decoder = {
    "rawvideo",
    CODEC_TYPE_VIDEO,
    CODEC_ID_RAWVIDEO,
    sizeof(RawVideoContext),
    raw_init_decoder,
    NULL,
    raw_close_decoder,
    raw_decode,
};