[FFmpeg-devel] [PATCH] PCX encoder

[Michael Niedermayer]

On Tue, Mar 17, 2009 at 01:14:50PM -0400, Daniel Verkamp wrote:
[...]
> +static int pcx_rle_encode(      uint8_t *dst, int dst_size,
> +                          const uint8_t *src, int src_size)
> +{
> +    int i;
> +    uint8_t prev = src[0];
> +    int count = 1;
> +    const uint8_t *dst_start = dst;
> +
> +    // check worst-case upper bound on dst_size
> +    if (dst_size < 2LL * src_size)
> +        return -1;
> +
> +    for (i = 1; ; i++) {
> +        if (i != src_size && src[i] == prev && count < 0x3F) {
> +            // current byte is same as prev
> +            ++count;
> +        } else {
> +            // output prev * count
> +            if (count != 1 || prev >= 0xC0)
> +                *dst++ = 0xC0 | count;
> +            *dst++ = prev;
> +
> +            if (i == src_size)
> +                return dst - dst_start;
> +
> +            // start new run
> +            count = 1;
> +            prev = src[i];
> +        }
> +    }
> +
> +    return 0; // gcc warns even though this cannot be reached

does gcc still warn with the current for() ?


> +}
> +
> +static int pcx_encode_frame(AVCodecContext *avctx,
> +                            unsigned char *buf, int buf_size, void *data)
> +{
> +    PCXContext *s = avctx->priv_data;
> +    AVFrame *const pict = &s->picture;
> +    const uint8_t *buf_start = buf;
> +    const uint8_t *buf_end   = buf + buf_size;
> +
> +    int bpp, nplanes, i, j, y, p, line_bytes, written, src_line_size;
> +    const uint32_t *pal = NULL;
> +    const uint8_t *src;
> +    uint8_t *plane;
> +
> +    *pict = *(AVFrame *)data;
> +    pict->pict_type = FF_I_TYPE;
> +    pict->key_frame = 1;
> +
> +    if (avctx->width > 65535 || avctx->height > 65535) {
> +        av_log(avctx, AV_LOG_ERROR, "image dimensions do not fit in 16 bits\n");
> +        return -1;
> +    }
> +
> +    switch (avctx->pix_fmt) {
> +    case PIX_FMT_RGB24:
> +        bpp = 8;
> +        nplanes = 3;
> +        break;
> +    case PIX_FMT_RGB8:
> +    case PIX_FMT_BGR8:
> +    case PIX_FMT_RGB4_BYTE:
> +    case PIX_FMT_BGR4_BYTE:
> +    case PIX_FMT_GRAY8:
> +    case PIX_FMT_PAL8:
> +        bpp = 8;
> +        nplanes = 1;
> +        pal = (uint32_t *)pict->data[1];
> +        break;
> +    case PIX_FMT_MONOBLACK:
> +        bpp = 1;
> +        nplanes = 1;
> +        pal = monoblack_pal;
> +        break;
> +    default:
> +        av_log(avctx, AV_LOG_ERROR, "unsupported pixfmt\n");
> +        return -1;
> +    }
> +
> +    line_bytes = (avctx->width * bpp + 7) >> 3;
> +    line_bytes = (line_bytes + 1) & ~1;
> +
> +    bytestream_put_byte(&buf, 10);                  // manufacturer
> +    bytestream_put_byte(&buf, 5);                   // version
> +    bytestream_put_byte(&buf, 1);                   // encoding
> +    bytestream_put_byte(&buf, bpp);                 // bits per pixel per plane
> +    bytestream_put_le16(&buf, 0);                   // x min
> +    bytestream_put_le16(&buf, 0);                   // y min
> +    bytestream_put_le16(&buf, avctx->width - 1);    // x max
> +    bytestream_put_le16(&buf, avctx->height - 1);   // y max
> +    bytestream_put_le16(&buf, 0);                   // horizontal DPI
> +    bytestream_put_le16(&buf, 0);                   // vertical DPI
> +    for (i = 0; i < 16; i++)
> +        bytestream_put_be24(&buf, pal ? pal[i] : 0);// palette (<= 16 color only)
> +    bytestream_put_byte(&buf, 0);                   // reserved
> +    bytestream_put_byte(&buf, nplanes);             // number of planes
> +    bytestream_put_le16(&buf, line_bytes);          // scanline plane size in bytes
> +
> +    while (buf - buf_start < 128)
> +        *buf++= 0;
> +
> +    plane = av_mallocz(line_bytes);
> +    src = pict->data[0];
> +    src_line_size = (avctx->width * nplanes * bpp + 7) >> 3;
> +
> +    for (y = 0; y < avctx->height; y++) {
> +        for (p = 0; p < nplanes; p++) {
> +            for (i = p, j = 0; i < src_line_size; i += nplanes, j++) {
> +                plane[j] = src[i];
> +            }
> +            if ((written = pcx_rle_encode(buf, buf_end - buf,
> +                                          plane, line_bytes)) < 0) {
> +                av_log(avctx, AV_LOG_ERROR, "buffer too small\n");
> +                av_free(plane);
> +                return -1;
> +            }

i think plane could be avoided by passing nplanes into pcx_rle_encode()
and i think that wouldnt make pcx_rle_encode uglier ...


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Avoid a single point of failure, be that a person or equipment.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20090318/bea2d7b6/attachment.pgp>