qtrle.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

                    rgb16 = AV_RB16(&s->buf[stream_ptr]);
                    stream_ptr += 2;
                    *(unsigned short *)(&rgb[pixel_ptr]) = rgb16;
                    pixel_ptr += 2;
                }
            }
        }
        row_ptr += row_inc;
    }
}

static void qtrle_decode_24bpp(QtrleContext *s)
{
    int stream_ptr;
    int header;
    int start_line;
    int lines_to_change;
    int rle_code;
    int row_ptr, pixel_ptr;
    int row_inc = s->frame.linesize[0];
    unsigned char r, g, b;
    unsigned char *rgb = s->frame.data[0];
    int pixel_limit = s->frame.linesize[0] * s->avctx->height;

    /* check if this frame is even supposed to change */
    if (s->size < 8)
        return;

    /* start after the chunk size */
    stream_ptr = 4;

    /* fetch the header */
    CHECK_STREAM_PTR(2);
    header = AV_RB16(&s->buf[stream_ptr]);
    stream_ptr += 2;

    /* if a header is present, fetch additional decoding parameters */
    if (header & 0x0008) {
        CHECK_STREAM_PTR(8);
        start_line = AV_RB16(&s->buf[stream_ptr]);
        stream_ptr += 4;
        lines_to_change = AV_RB16(&s->buf[stream_ptr]);
        stream_ptr += 4;
    } else {
        start_line = 0;
        lines_to_change = s->avctx->height;
    }

    row_ptr = row_inc * start_line;
    while (lines_to_change--) {
        CHECK_STREAM_PTR(2);
        pixel_ptr = row_ptr + (s->buf[stream_ptr++] - 1) * 3;

        while ((rle_code = (signed char)s->buf[stream_ptr++]) != -1) {
            if (rle_code == 0) {
                /* there's another skip code in the stream */
                CHECK_STREAM_PTR(1);
                pixel_ptr += (s->buf[stream_ptr++] - 1) * 3;
                CHECK_PIXEL_PTR(0);  /* make sure pixel_ptr is positive */
            } else if (rle_code < 0) {
                /* decode the run length code */
                rle_code = -rle_code;
                CHECK_STREAM_PTR(3);
                r = s->buf[stream_ptr++];
                g = s->buf[stream_ptr++];
                b = s->buf[stream_ptr++];

                CHECK_PIXEL_PTR(rle_code * 3);

                while (rle_code--) {
                    rgb[pixel_ptr++] = r;
                    rgb[pixel_ptr++] = g;
                    rgb[pixel_ptr++] = b;
                }
            } else {
                CHECK_STREAM_PTR(rle_code * 3);
                CHECK_PIXEL_PTR(rle_code * 3);

                /* copy pixels directly to output */
                while (rle_code--) {
                    rgb[pixel_ptr++] = s->buf[stream_ptr++];
                    rgb[pixel_ptr++] = s->buf[stream_ptr++];
                    rgb[pixel_ptr++] = s->buf[stream_ptr++];
                }
            }
        }
        row_ptr += row_inc;
    }
}

static void qtrle_decode_32bpp(QtrleContext *s)
{
    int stream_ptr;
    int header;
    int start_line;
    int lines_to_change;
    int rle_code;
    int row_ptr, pixel_ptr;
    int row_inc = s->frame.linesize[0];
    unsigned char a, r, g, b;
    unsigned int argb;
    unsigned char *rgb = s->frame.data[0];
    int pixel_limit = s->frame.linesize[0] * s->avctx->height;

    /* check if this frame is even supposed to change */
    if (s->size < 8)
        return;

    /* start after the chunk size */
    stream_ptr = 4;

    /* fetch the header */
    CHECK_STREAM_PTR(2);
    header = AV_RB16(&s->buf[stream_ptr]);
    stream_ptr += 2;

    /* if a header is present, fetch additional decoding parameters */
    if (header & 0x0008) {
        CHECK_STREAM_PTR(8);
        start_line = AV_RB16(&s->buf[stream_ptr]);
        stream_ptr += 4;
        lines_to_change = AV_RB16(&s->buf[stream_ptr]);
        stream_ptr += 4;
    } else {
        start_line = 0;
        lines_to_change = s->avctx->height;
    }

    row_ptr = row_inc * start_line;
    while (lines_to_change--) {
        CHECK_STREAM_PTR(2);
        pixel_ptr = row_ptr + (s->buf[stream_ptr++] - 1) * 4;

        while ((rle_code = (signed char)s->buf[stream_ptr++]) != -1) {
            if (rle_code == 0) {
                /* there's another skip code in the stream */
                CHECK_STREAM_PTR(1);
                pixel_ptr += (s->buf[stream_ptr++] - 1) * 4;
                CHECK_PIXEL_PTR(0);  /* make sure pixel_ptr is positive */
            } else if (rle_code < 0) {
                /* decode the run length code */
                rle_code = -rle_code;
                CHECK_STREAM_PTR(4);
                a = s->buf[stream_ptr++];
                r = s->buf[stream_ptr++];
                g = s->buf[stream_ptr++];
                b = s->buf[stream_ptr++];
                argb = (a << 24) | (r << 16) | (g << 8) | (b << 0);

                CHECK_PIXEL_PTR(rle_code * 4);

                while (rle_code--) {
                    *(unsigned int *)(&rgb[pixel_ptr]) = argb;
                    pixel_ptr += 4;
                }
            } else {
                CHECK_STREAM_PTR(rle_code * 4);
                CHECK_PIXEL_PTR(rle_code * 4);

                /* copy pixels directly to output */
                while (rle_code--) {
                    a = s->buf[stream_ptr++];
                    r = s->buf[stream_ptr++];
                    g = s->buf[stream_ptr++];
                    b = s->buf[stream_ptr++];
                    argb = (a << 24) | (r << 16) | (g << 8) | (b << 0);
                    *(unsigned int *)(&rgb[pixel_ptr]) = argb;
                    pixel_ptr += 4;
                }
            }
        }
        row_ptr += row_inc;
    }
}

static int qtrle_decode_init(AVCodecContext *avctx)
{
    QtrleContext *s = avctx->priv_data;

    s->avctx = avctx;
    switch (avctx->bits_per_sample) {
    case 1:
    case 2:
    case 4:
    case 8:
    case 33:
    case 34:
    case 36:
    case 40:
        avctx->pix_fmt = PIX_FMT_PAL8;
        break;

    case 16:
        avctx->pix_fmt = PIX_FMT_RGB555;
        break;

    case 24:
        avctx->pix_fmt = PIX_FMT_RGB24;
        break;

    case 32:
        avctx->pix_fmt = PIX_FMT_RGB32;
        break;

    default:
        av_log (avctx, AV_LOG_ERROR, "Unsupported colorspace: %d bits/sample?\n",
            avctx->bits_per_sample);
        break;
    }
    dsputil_init(&s->dsp, avctx);

    s->frame.data[0] = NULL;

    return 0;
}

static int qtrle_decode_frame(AVCodecContext *avctx,
                              void *data, int *data_size,
                              uint8_t *buf, int buf_size)
{
    QtrleContext *s = avctx->priv_data;

    s->buf = buf;
    s->size = buf_size;

    s->frame.reference = 1;
    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
                            FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
    if (avctx->reget_buffer(avctx, &s->frame)) {
        av_log (s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return -1;
    }

    switch (avctx->bits_per_sample) {
    case 1:
    case 33:
        qtrle_decode_1bpp(s);
        break;

    case 2:
    case 34:
        qtrle_decode_2bpp(s);
        break;

    case 4:
    case 36:
        qtrle_decode_4bpp(s);
        /* make the palette available on the way out */
        memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
        if (s->avctx->palctrl->palette_changed) {
            s->frame.palette_has_changed = 1;
            s->avctx->palctrl->palette_changed = 0;
        }
        break;

    case 8:
    case 40:
        qtrle_decode_8bpp(s);
        /* make the palette available on the way out */
        memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
        if (s->avctx->palctrl->palette_changed) {
            s->frame.palette_has_changed = 1;
            s->avctx->palctrl->palette_changed = 0;
        }
        break;

    case 16:
        qtrle_decode_16bpp(s);
        break;

    case 24:
        qtrle_decode_24bpp(s);
        break;

    case 32:
        qtrle_decode_32bpp(s);
        break;

    default:
        av_log (s->avctx, AV_LOG_ERROR, "Unsupported colorspace: %d bits/sample?\n",
            avctx->bits_per_sample);
        break;
    }

    *data_size = sizeof(AVFrame);
    *(AVFrame*)data = s->frame;

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

static int qtrle_decode_end(AVCodecContext *avctx)
{
    QtrleContext *s = avctx->priv_data;

    if (s->frame.data[0])
        avctx->release_buffer(avctx, &s->frame);

    return 0;
}

AVCodec qtrle_decoder = {
    "qtrle",
    CODEC_TYPE_VIDEO,
    CODEC_ID_QTRLE,
    sizeof(QtrleContext),
    qtrle_decode_init,
    NULL,
    qtrle_decode_end,
    qtrle_decode_frame,
    CODEC_CAP_DR1,
};