flicvideo.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

        case FLI_COPY:
            /* copy the chunk (uncompressed frame) */
            if (chunk_size - 6 > s->avctx->width * s->avctx->height) {
                av_log(avctx, AV_LOG_ERROR, "In chunk FLI_COPY : source data (%d bytes) " \
                       "bigger than image, skipping chunk\n", chunk_size - 6);
                stream_ptr += chunk_size - 6;
            } else {
                for (y_ptr = 0; y_ptr < s->frame.linesize[0] * s->avctx->height;
                     y_ptr += s->frame.linesize[0]) {
                    memcpy(&pixels[y_ptr], &buf[stream_ptr],
                        s->avctx->width);
                    stream_ptr += s->avctx->width;
                }
            }
            break;

        case FLI_MINI:
            /* some sort of a thumbnail? disregard this chunk... */
            stream_ptr += chunk_size - 6;
            break;

        default:
            av_log(avctx, AV_LOG_ERROR, "Unrecognized chunk type: %d\n", chunk_type);
            break;
        }

        frame_size -= chunk_size;
        num_chunks--;
    }

    /* by the end of the chunk, the stream ptr should equal the frame
     * size (minus 1, possibly); if it doesn't, issue a warning */
    if ((stream_ptr != buf_size) && (stream_ptr != buf_size - 1))
        av_log(avctx, AV_LOG_ERROR, "Processed FLI chunk where chunk size = %d " \
               "and final chunk ptr = %d\n", buf_size, stream_ptr);

    /* make the palette available on the way out */
    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
    if (s->new_palette) {
        s->frame.palette_has_changed = 1;
        s->new_palette = 0;
    }

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

    return buf_size;
}

static int flic_decode_frame_15_16BPP(AVCodecContext *avctx,
                                      void *data, int *data_size,
                                      uint8_t *buf, int buf_size)
{
    /* Note, the only difference between the 15Bpp and 16Bpp */
    /* Format is the pixel format, the packets are processed the same. */
    FlicDecodeContext *s = avctx->priv_data;

    int stream_ptr = 0;
    int pixel_ptr;
    unsigned char palette_idx1;

    unsigned int frame_size;
    int num_chunks;

    unsigned int chunk_size;
    int chunk_type;

    int i, j;

    int lines;
    int compressed_lines;
    signed short line_packets;
    int y_ptr;
    int byte_run;
    int pixel_skip;
    int pixel_countdown;
    unsigned char *pixels;
    int pixel;
    int pixel_limit;

    s->frame.reference = 1;
    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
    if (avctx->reget_buffer(avctx, &s->frame) < 0) {
        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return -1;
    }

    pixels = s->frame.data[0];
    pixel_limit = s->avctx->height * s->frame.linesize[0];

    frame_size = AV_RL32(&buf[stream_ptr]);
    stream_ptr += 6;  /* skip the magic number */
    num_chunks = AV_RL16(&buf[stream_ptr]);
    stream_ptr += 10;  /* skip padding */

    frame_size -= 16;

    /* iterate through the chunks */
    while ((frame_size > 0) && (num_chunks > 0)) {
        chunk_size = AV_RL32(&buf[stream_ptr]);
        stream_ptr += 4;
        chunk_type = AV_RL16(&buf[stream_ptr]);
        stream_ptr += 2;

        switch (chunk_type) {
        case FLI_256_COLOR:
        case FLI_COLOR:
            /* For some reason, it seems that non-paletised flics do include one of these */
            /* chunks in their first frame.  Why i do not know, it seems rather extraneous */
/*            av_log(avctx, AV_LOG_ERROR, "Unexpected Palette chunk %d in non-paletised FLC\n",chunk_type);*/
            stream_ptr = stream_ptr + chunk_size - 6;
            break;

        case FLI_DELTA:
        case FLI_DTA_LC:
            y_ptr = 0;
            compressed_lines = AV_RL16(&buf[stream_ptr]);
            stream_ptr += 2;
            while (compressed_lines > 0) {
                line_packets = AV_RL16(&buf[stream_ptr]);
                stream_ptr += 2;
                if (line_packets < 0) {
                    line_packets = -line_packets;
                    y_ptr += line_packets * s->frame.linesize[0];
                } else {
                    compressed_lines--;
                    pixel_ptr = y_ptr;
                    pixel_countdown = s->avctx->width;
                    for (i = 0; i < line_packets; i++) {
                        /* account for the skip bytes */
                        pixel_skip = buf[stream_ptr++];
                        pixel_ptr += (pixel_skip*2); /* Pixel is 2 bytes wide */
                        pixel_countdown -= pixel_skip;
                        byte_run = (signed char)(buf[stream_ptr++]);
                        if (byte_run < 0) {
                            byte_run = -byte_run;
                            pixel    = AV_RL16(&buf[stream_ptr]);
                            stream_ptr += 2;
                            CHECK_PIXEL_PTR(byte_run);
                            for (j = 0; j < byte_run; j++, pixel_countdown -= 2) {
                                *((signed short*)(&pixels[pixel_ptr])) = pixel;
                                pixel_ptr += 2;
                            }
                        } else {
                            CHECK_PIXEL_PTR(byte_run);
                            for (j = 0; j < byte_run; j++, pixel_countdown--) {
                                *((signed short*)(&pixels[pixel_ptr])) = AV_RL16(&buf[stream_ptr]);
                                stream_ptr += 2;
                                pixel_ptr += 2;
                            }
                        }
                    }

                    y_ptr += s->frame.linesize[0];
                }
            }
            break;

        case FLI_LC:
            av_log(avctx, AV_LOG_ERROR, "Unexpected FLI_LC chunk in non-paletised FLC\n");
            stream_ptr = stream_ptr + chunk_size - 6;
            break;

        case FLI_BLACK:
            /* set the whole frame to 0x0000 which is black in both 15Bpp and 16Bpp modes. */
            memset(pixels, 0x0000,
                   s->frame.linesize[0] * s->avctx->height);
            break;

        case FLI_BRUN:
            y_ptr = 0;
            for (lines = 0; lines < s->avctx->height; lines++) {
                pixel_ptr = y_ptr;
                /* disregard the line packets; instead, iterate through all
                 * pixels on a row */
                stream_ptr++;
                pixel_countdown = (s->avctx->width * 2);

                while (pixel_countdown > 0) {
                    byte_run = (signed char)(buf[stream_ptr++]);
                    if (byte_run > 0) {
                        palette_idx1 = buf[stream_ptr++];
                        CHECK_PIXEL_PTR(byte_run);
                        for (j = 0; j < byte_run; j++) {
                            pixels[pixel_ptr++] = palette_idx1;
                            pixel_countdown--;
                            if (pixel_countdown < 0)
                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d) (linea%d)\n",
                                       pixel_countdown, lines);
                        }
                    } else {  /* copy bytes if byte_run < 0 */
                        byte_run = -byte_run;
                        CHECK_PIXEL_PTR(byte_run);
                        for (j = 0; j < byte_run; j++) {
                            palette_idx1 = buf[stream_ptr++];
                            pixels[pixel_ptr++] = palette_idx1;
                            pixel_countdown--;
                            if (pixel_countdown < 0)
                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d) at line %d\n",
                                       pixel_countdown, lines);
                        }
                    }
                }

                /* Now FLX is strange, in that it is "byte" as opposed to "pixel" run length compressed.
                 * This does not give us any good oportunity to perform word endian conversion
                 * during decompression. So if it is required (i.e., this is not a LE target, we do
                 * a second pass over the line here, swapping the bytes.
                 */
#ifdef WORDS_BIGENDIAN
                pixel_ptr = y_ptr;
                pixel_countdown = s->avctx->width;
                while (pixel_countdown > 0) {
                    *((signed short*)(&pixels[pixel_ptr])) = AV_RL16(&buf[pixel_ptr]);
                    pixel_ptr += 2;
                }
#endif
                y_ptr += s->frame.linesize[0];
            }
            break;

        case FLI_DTA_BRUN:
            y_ptr = 0;
            for (lines = 0; lines < s->avctx->height; lines++) {
                pixel_ptr = y_ptr;
                /* disregard the line packets; instead, iterate through all
                 * pixels on a row */
                stream_ptr++;
                pixel_countdown = s->avctx->width; /* Width is in pixels, not bytes */

                while (pixel_countdown > 0) {
                    byte_run = (signed char)(buf[stream_ptr++]);
                    if (byte_run > 0) {
                        pixel    = AV_RL16(&buf[stream_ptr]);
                        stream_ptr += 2;
                        CHECK_PIXEL_PTR(byte_run);
                        for (j = 0; j < byte_run; j++) {
                            *((signed short*)(&pixels[pixel_ptr])) = pixel;
                            pixel_ptr += 2;
                            pixel_countdown--;
                            if (pixel_countdown < 0)
                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d)\n",
                                       pixel_countdown);
                        }
                    } else {  /* copy pixels if byte_run < 0 */
                        byte_run = -byte_run;
                        CHECK_PIXEL_PTR(byte_run);
                        for (j = 0; j < byte_run; j++) {
                            *((signed short*)(&pixels[pixel_ptr])) = AV_RL16(&buf[stream_ptr]);
                            stream_ptr += 2;
                            pixel_ptr  += 2;
                            pixel_countdown--;
                            if (pixel_countdown < 0)
                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d)\n",
                                       pixel_countdown);
                        }
                    }
                }

                y_ptr += s->frame.linesize[0];
            }
            break;

        case FLI_COPY:
        case FLI_DTA_COPY:
            /* copy the chunk (uncompressed frame) */
            if (chunk_size - 6 > (unsigned int)(s->avctx->width * s->avctx->height)*2) {
                av_log(avctx, AV_LOG_ERROR, "In chunk FLI_COPY : source data (%d bytes) " \
                       "bigger than image, skipping chunk\n", chunk_size - 6);
                stream_ptr += chunk_size - 6;
            } else {

                for (y_ptr = 0; y_ptr < s->frame.linesize[0] * s->avctx->height;
                     y_ptr += s->frame.linesize[0]) {

                    pixel_countdown = s->avctx->width;
                    pixel_ptr = 0;
                    while (pixel_countdown > 0) {
                      *((signed short*)(&pixels[y_ptr + pixel_ptr])) = AV_RL16(&buf[stream_ptr+pixel_ptr]);
                      pixel_ptr += 2;
                      pixel_countdown--;
                    }
                    stream_ptr += s->avctx->width*2;
                }
            }
            break;

        case FLI_MINI:
            /* some sort of a thumbnail? disregard this chunk... */
            stream_ptr += chunk_size - 6;
            break;

        default:
            av_log(avctx, AV_LOG_ERROR, "Unrecognized chunk type: %d\n", chunk_type);
            break;
        }

        frame_size -= chunk_size;
        num_chunks--;
    }

    /* by the end of the chunk, the stream ptr should equal the frame
     * size (minus 1, possibly); if it doesn't, issue a warning */
    if ((stream_ptr != buf_size) && (stream_ptr != buf_size - 1))
        av_log(avctx, AV_LOG_ERROR, "Processed FLI chunk where chunk size = %d " \
               "and final chunk ptr = %d\n", buf_size, stream_ptr);


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

    return buf_size;
}

static int flic_decode_frame_24BPP(AVCodecContext *avctx,
                                   void *data, int *data_size,
                                   uint8_t *buf, int buf_size)
{
  av_log(avctx, AV_LOG_ERROR, "24Bpp FLC Unsupported due to lack of test files.\n");
  return -1;
}

static int flic_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,
                             uint8_t *buf, int buf_size)
{
    if (avctx->pix_fmt == PIX_FMT_PAL8) {
      return flic_decode_frame_8BPP(avctx, data, data_size,
                                    buf, buf_size);
    }
    else if ((avctx->pix_fmt == PIX_FMT_RGB555) ||
             (avctx->pix_fmt == PIX_FMT_RGB565)) {
      return flic_decode_frame_15_16BPP(avctx, data, data_size,
                                        buf, buf_size);
    }
    else if (avctx->pix_fmt == PIX_FMT_BGR24) {
      return flic_decode_frame_24BPP(avctx, data, data_size,
                                     buf, buf_size);
    }

    /* Should not get  here, ever as the pix_fmt is processed */
    /* in flic_decode_init and the above if should deal with */
    /* the finite set of possibilites allowable by here. */
    /* But in case we do, just error out. */
    av_log(avctx, AV_LOG_ERROR, "Unknown FLC format, my science cannot explain how this happened.\n");
    return -1;
}


static int flic_decode_end(AVCodecContext *avctx)
{
    FlicDecodeContext *s = avctx->priv_data;

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

    return 0;
}

AVCodec flic_decoder = {
    "flic",
    CODEC_TYPE_VIDEO,
    CODEC_ID_FLIC,
    sizeof(FlicDecodeContext),
    flic_decode_init,
    NULL,
    flic_decode_end,
    flic_decode_frame,
    CODEC_CAP_DR1,
    NULL,
    NULL,
    NULL,
    NULL
};