pcxenc.c

/*
 * PC Paintbrush PCX (.pcx) image encoder
 * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * PCX image encoder
 * @author Daniel Verkamp
 * @see http://www.qzx.com/pc-gpe/pcx.txt
 */

#include "avcodec.h"
#include "bytestream.h"

typedef struct PCXContext {
    AVFrame picture;
} PCXContext;

static const uint32_t monoblack_pal[16] = { 0x000000, 0xFFFFFF };

static av_cold int pcx_encode_init(AVCodecContext *avctx)
{
    PCXContext *s = avctx->priv_data;

    avcodec_get_frame_defaults(&s->picture);
    avctx->coded_frame = &s->picture;

    return 0;
}

/**
 * PCX run-length encoder
 * @param dst output buffer
 * @param dst_size size of output buffer
 * @param src input buffer
 * @param src_plane_size size of one plane of input buffer in bytes
 * @param nplanes number of planes in input buffer
 * @return number of bytes written to dst or -1 on error
 * @bug will not work for nplanes != 1 && bpp != 8
 */
static int pcx_rle_encode(      uint8_t *dst, int dst_size,
                          const uint8_t *src, int src_plane_size, int nplanes)
{
    int p;
    const uint8_t *dst_start = dst;

    // check worst-case upper bound on dst_size
    if (dst_size < 2LL * src_plane_size * nplanes || src_plane_size <= 0)
        return -1;

    for (p = 0; p < nplanes; p++) {
        int count = 1;
        const uint8_t *src_plane = src + p;
        const uint8_t *src_plane_end = src_plane + src_plane_size * nplanes;
        uint8_t prev = *src_plane;
        src_plane += nplanes;

        for (; ; src_plane += nplanes) {
            if (src_plane < src_plane_end && *src_plane == 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 (src_plane == src_plane_end)
                    break;

                // start new run
                count = 1;
                prev = *src_plane;
            }
        }
    }

    return dst - dst_start;
}

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, y, line_bytes, written;
    const uint32_t *pal = NULL;
    const uint8_t *src;

    *pict = *(AVFrame *)data;
    pict->pict_type = AV_PICTURE_TYPE_I;
    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;

    src = pict->data[0];

    for (y = 0; y < avctx->height; y++) {
        if ((written = pcx_rle_encode(buf, buf_end - buf,
                                      src, line_bytes, nplanes)) < 0) {
            av_log(avctx, AV_LOG_ERROR, "buffer too small\n");
            return -1;
        }
        buf += written;
        src += pict->linesize[0];
    }

    if (nplanes == 1 && bpp == 8) {
        if (buf_end - buf < 257) {
            av_log(avctx, AV_LOG_ERROR, "buffer too small\n");
            return -1;
        }
        bytestream_put_byte(&buf, 12);
        for (i = 0; i < 256; i++) {
            bytestream_put_be24(&buf, pal[i]);
        }
    }

    return buf - buf_start;
}

AVCodec ff_pcx_encoder = {
    .name           = "pcx",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_PCX,
    .priv_data_size = sizeof(PCXContext),
    .init           = pcx_encode_init,
    .encode         = pcx_encode_frame,
    .pix_fmts = (const enum PixelFormat[]){
        PIX_FMT_RGB24,
        PIX_FMT_RGB8, PIX_FMT_BGR8, PIX_FMT_RGB4_BYTE, PIX_FMT_BGR4_BYTE, PIX_FMT_GRAY8, PIX_FMT_PAL8,
        PIX_FMT_MONOBLACK,
        PIX_FMT_NONE},
    .long_name = NULL_IF_CONFIG_SMALL("PC Paintbrush PCX image"),
};