mjpegdec.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

                //        if (s->first_picture)
                //            printf("mjpeg: workarounding buggy AVID\n");
            }
            else if(!strcmp(cbuf, "CS=ITU601")){
                s->cs_itu601= 1;
            }

            av_free(cbuf);
        }
    }

    return 0;
}

#if 0
static int valid_marker_list[] =
{
        /* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f */
/* 0 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 1 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 2 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 3 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 4 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 5 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 6 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 7 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 8 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 9 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* a */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* b */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* c */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* d */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* e */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* f */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
}
#endif

/* return the 8 bit start code value and update the search
   state. Return -1 if no start code found */
static int find_marker(uint8_t **pbuf_ptr, uint8_t *buf_end)
{
    uint8_t *buf_ptr;
    unsigned int v, v2;
    int val;
#ifdef DEBUG
    int skipped=0;
#endif

    buf_ptr = *pbuf_ptr;
    while (buf_ptr < buf_end) {
        v = *buf_ptr++;
        v2 = *buf_ptr;
        if ((v == 0xff) && (v2 >= 0xc0) && (v2 <= 0xfe) && buf_ptr < buf_end) {
            val = *buf_ptr++;
            goto found;
        }
#ifdef DEBUG
        skipped++;
#endif
    }
    val = -1;
found:
#ifdef DEBUG
    av_log(NULL, AV_LOG_VERBOSE, "find_marker skipped %d bytes\n", skipped);
#endif
    *pbuf_ptr = buf_ptr;
    return val;
}

int ff_mjpeg_decode_frame(AVCodecContext *avctx,
                              void *data, int *data_size,
                              uint8_t *buf, int buf_size)
{
    MJpegDecodeContext *s = avctx->priv_data;
    uint8_t *buf_end, *buf_ptr;
    int start_code;
    AVFrame *picture = data;

    buf_ptr = buf;
    buf_end = buf + buf_size;
    while (buf_ptr < buf_end) {
        /* find start next marker */
        start_code = find_marker(&buf_ptr, buf_end);
        {
            /* EOF */
            if (start_code < 0) {
                goto the_end;
            } else {
                av_log(avctx, AV_LOG_DEBUG, "marker=%x avail_size_in_buf=%td\n", start_code, buf_end - buf_ptr);

                if ((buf_end - buf_ptr) > s->buffer_size)
                {
                    av_free(s->buffer);
                    s->buffer_size = buf_end-buf_ptr;
                    s->buffer = av_malloc(s->buffer_size + FF_INPUT_BUFFER_PADDING_SIZE);
                    av_log(avctx, AV_LOG_DEBUG, "buffer too small, expanding to %d bytes\n",
                        s->buffer_size);
                }

                /* unescape buffer of SOS, use special treatment for JPEG-LS */
                if (start_code == SOS && !s->ls)
                {
                    uint8_t *src = buf_ptr;
                    uint8_t *dst = s->buffer;

                    while (src<buf_end)
                    {
                        uint8_t x = *(src++);

                        *(dst++) = x;
                        if (avctx->codec_id != CODEC_ID_THP)
                        {
                            if (x == 0xff) {
                                while (src < buf_end && x == 0xff)
                                    x = *(src++);

                                if (x >= 0xd0 && x <= 0xd7)
                                    *(dst++) = x;
                                else if (x)
                                    break;
                            }
                        }
                    }
                    init_get_bits(&s->gb, s->buffer, (dst - s->buffer)*8);

                    av_log(avctx, AV_LOG_DEBUG, "escaping removed %td bytes\n",
                           (buf_end - buf_ptr) - (dst - s->buffer));
                }
                else if(start_code == SOS && s->ls){
                    uint8_t *src = buf_ptr;
                    uint8_t *dst = s->buffer;
                    int bit_count = 0;
                    int t = 0, b = 0;
                    PutBitContext pb;

                    s->cur_scan++;

                    /* find marker */
                    while (src + t < buf_end){
                        uint8_t x = src[t++];
                        if (x == 0xff){
                            while((src + t < buf_end) && x == 0xff)
                                x = src[t++];
                            if (x & 0x80) {
                                t -= 2;
                                break;
                            }
                        }
                    }
                    bit_count = t * 8;

                    init_put_bits(&pb, dst, t);

                    /* unescape bitstream */
                    while(b < t){
                        uint8_t x = src[b++];
                        put_bits(&pb, 8, x);
                        if(x == 0xFF){
                            x = src[b++];
                            put_bits(&pb, 7, x);
                            bit_count--;
                        }
                    }
                    flush_put_bits(&pb);

                    init_get_bits(&s->gb, dst, bit_count);
                }
                else
                    init_get_bits(&s->gb, buf_ptr, (buf_end - buf_ptr)*8);

                s->start_code = start_code;
                if(s->avctx->debug & FF_DEBUG_STARTCODE){
                    av_log(avctx, AV_LOG_DEBUG, "startcode: %X\n", start_code);
                }

                /* process markers */
                if (start_code >= 0xd0 && start_code <= 0xd7) {
                    av_log(avctx, AV_LOG_DEBUG, "restart marker: %d\n", start_code&0x0f);
                    /* APP fields */
                } else if (start_code >= APP0 && start_code <= APP15) {
                    mjpeg_decode_app(s);
                    /* Comment */
                } else if (start_code == COM){
                    mjpeg_decode_com(s);
                }

                switch(start_code) {
                case SOI:
                    s->restart_interval = 0;

                    s->restart_count = 0;
                    /* nothing to do on SOI */
                    break;
                case DQT:
                    ff_mjpeg_decode_dqt(s);
                    break;
                case DHT:
                    if(ff_mjpeg_decode_dht(s) < 0){
                        av_log(avctx, AV_LOG_ERROR, "huffman table decode error\n");
                        return -1;
                    }
                    break;
                case SOF0:
                    s->lossless=0;
                    s->ls=0;
                    s->progressive=0;
                    if (ff_mjpeg_decode_sof(s) < 0)
                        return -1;
                    break;
                case SOF2:
                    s->lossless=0;
                    s->ls=0;
                    s->progressive=1;
                    if (ff_mjpeg_decode_sof(s) < 0)
                        return -1;
                    break;
                case SOF3:
                    s->lossless=1;
                    s->ls=0;
                    s->progressive=0;
                    if (ff_mjpeg_decode_sof(s) < 0)
                        return -1;
                    break;
                case SOF48:
                    s->lossless=1;
                    s->ls=1;
                    s->progressive=0;
                    if (ff_mjpeg_decode_sof(s) < 0)
                        return -1;
                    break;
                case LSE:
                    if (!ENABLE_JPEGLS_DECODER || ff_jpegls_decode_lse(s) < 0)
                        return -1;
                    break;
                case EOI:
                    s->cur_scan = 0;
                    if ((s->buggy_avid && !s->interlaced) || s->restart_interval)
                        break;
eoi_parser:
                    {
                        if (s->interlaced) {
                            s->bottom_field ^= 1;
                            /* if not bottom field, do not output image yet */
                            if (s->bottom_field == !s->interlace_polarity)
                                goto not_the_end;
                        }
                        *picture = s->picture;
                        *data_size = sizeof(AVFrame);

                        if(!s->lossless){
                            picture->quality= FFMAX(FFMAX(s->qscale[0], s->qscale[1]), s->qscale[2]);
                            picture->qstride= 0;
                            picture->qscale_table= s->qscale_table;
                            memset(picture->qscale_table, picture->quality, (s->width+15)/16);
                            if(avctx->debug & FF_DEBUG_QP)
                                av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
                            picture->quality*= FF_QP2LAMBDA;
                        }

                        goto the_end;
                    }
                    break;
                case SOS:
                    ff_mjpeg_decode_sos(s);
                    /* buggy avid puts EOI every 10-20th frame */
                    /* if restart period is over process EOI */
                    if ((s->buggy_avid && !s->interlaced) || s->restart_interval)
                        goto eoi_parser;
                    break;
                case DRI:
                    mjpeg_decode_dri(s);
                    break;
                case SOF1:
                case SOF5:
                case SOF6:
                case SOF7:
                case SOF9:
                case SOF10:
                case SOF11:
                case SOF13:
                case SOF14:
                case SOF15:
                case JPG:
                    av_log(avctx, AV_LOG_ERROR, "mjpeg: unsupported coding type (%x)\n", start_code);
                    break;
//                default:
//                    printf("mjpeg: unsupported marker (%x)\n", start_code);
//                    break;
                }

not_the_end:
                /* eof process start code */
                buf_ptr += (get_bits_count(&s->gb)+7)/8;
                av_log(avctx, AV_LOG_DEBUG, "marker parser used %d bytes (%d bits)\n",
                       (get_bits_count(&s->gb)+7)/8, get_bits_count(&s->gb));
            }
        }
    }
the_end:
    av_log(avctx, AV_LOG_DEBUG, "mjpeg decode frame unused %td bytes\n", buf_end - buf_ptr);
//    return buf_end - buf_ptr;
    return buf_ptr - buf;
}

int ff_mjpeg_decode_end(AVCodecContext *avctx)
{
    MJpegDecodeContext *s = avctx->priv_data;
    int i, j;

    av_free(s->buffer);
    av_free(s->qscale_table);

    for(i=0;i<2;i++) {
        for(j=0;j<4;j++)
            free_vlc(&s->vlcs[i][j]);
    }
    return 0;
}

AVCodec mjpeg_decoder = {
    "mjpeg",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MJPEG,
    sizeof(MJpegDecodeContext),
    ff_mjpeg_decode_init,
    NULL,
    ff_mjpeg_decode_end,
    ff_mjpeg_decode_frame,
    CODEC_CAP_DR1,
    NULL
};

AVCodec thp_decoder = {
    "thp",
    CODEC_TYPE_VIDEO,
    CODEC_ID_THP,
    sizeof(MJpegDecodeContext),
    ff_mjpeg_decode_init,
    NULL,
    ff_mjpeg_decode_end,
    ff_mjpeg_decode_frame,
    CODEC_CAP_DR1,
    NULL
};