pcx.c

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/*
 * PC Paintbrush PCX (.pcx) image decoder
 * Copyright (c) 2007, 2008 Ivo van Poorten
 *
 * This decoder does not support CGA palettes. I am unable to find samples
 * and Netpbm cannot generate them.
 *
 * 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
 */

#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "get_bits.h"
#include "internal.h"

static void pcx_rle_decode(GetByteContext *gb, uint8_t *dst,
                           unsigned int bytes_per_scanline, int compressed)
{
    unsigned int i = 0;
    unsigned char run, value;

    if (compressed) {
        while (i<bytes_per_scanline) {
            run = 1;
            value = bytestream2_get_byte(gb);
            if (value >= 0xc0) {
                run = value & 0x3f;
                value = bytestream2_get_byte(gb);
            }
            while (i<bytes_per_scanline && run--)
                dst[i++] = value;
        }
    } else {
        bytestream2_get_buffer(gb, dst, bytes_per_scanline);
    }
}

static void pcx_palette(GetByteContext *gb, uint32_t *dst, int pallen)
{
    int i;

    pallen = FFMIN(pallen, bytestream2_get_bytes_left(gb) / 3);
    for (i=0; i<pallen; i++)
        *dst++ = 0xFF000000 | bytestream2_get_be24u(gb);
    if (pallen < 256)
        memset(dst, 0, (256 - pallen) * sizeof(*dst));
}

static int pcx_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                            AVPacket *avpkt) {
    GetByteContext gb;
    AVFrame * const p = data;
    int compressed, xmin, ymin, xmax, ymax, ret;
    unsigned int w, h, bits_per_pixel, bytes_per_line, nplanes, stride, y, x,
                 bytes_per_scanline;
    uint8_t *ptr, *scanline;

    if (avpkt->size < 128)
        return AVERROR_INVALIDDATA;

    bytestream2_init(&gb, avpkt->data, avpkt->size);

    if (bytestream2_get_byteu(&gb) != 0x0a || bytestream2_get_byteu(&gb) > 5) {
        av_log(avctx, AV_LOG_ERROR, "this is not PCX encoded data\n");
        return AVERROR_INVALIDDATA;
    }

    compressed = bytestream2_get_byteu(&gb);
    bits_per_pixel = bytestream2_get_byteu(&gb);
    xmin = bytestream2_get_le16u(&gb);
    ymin = bytestream2_get_le16u(&gb);
    xmax = bytestream2_get_le16u(&gb);
    ymax = bytestream2_get_le16u(&gb);
    avctx->sample_aspect_ratio.num = bytestream2_get_le16u(&gb);
    avctx->sample_aspect_ratio.den = bytestream2_get_le16u(&gb);

    if (xmax < xmin || ymax < ymin) {
        av_log(avctx, AV_LOG_ERROR, "invalid image dimensions\n");
        return AVERROR_INVALIDDATA;
    }

    w = xmax - xmin + 1;
    h = ymax - ymin + 1;

    bytestream2_skipu(&gb, 49);
    nplanes            = bytestream2_get_byteu(&gb);
    bytes_per_line     = bytestream2_get_le16u(&gb);
    bytes_per_scanline = nplanes * bytes_per_line;

    if (bytes_per_scanline < (w * bits_per_pixel * nplanes + 7) / 8) {
        av_log(avctx, AV_LOG_ERROR, "PCX data is corrupted\n");
        return AVERROR_INVALIDDATA;
    }

    switch ((nplanes<<8) + bits_per_pixel) {
        case 0x0308:
            avctx->pix_fmt = AV_PIX_FMT_RGB24;
            break;
        case 0x0108:
        case 0x0104:
        case 0x0102:
        case 0x0101:
        case 0x0401:
        case 0x0301:
        case 0x0201:
            avctx->pix_fmt = AV_PIX_FMT_PAL8;
            break;
        default:
            av_log(avctx, AV_LOG_ERROR, "invalid PCX file\n");
            return AVERROR_INVALIDDATA;
    }

    bytestream2_skipu(&gb, 60);

    if ((ret = av_image_check_size(w, h, 0, avctx)) < 0)
        return ret;
    if (w != avctx->width || h != avctx->height)
        avcodec_set_dimensions(avctx, w, h);
    if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
        return ret;

    p->pict_type = AV_PICTURE_TYPE_I;

    ptr    = p->data[0];
    stride = p->linesize[0];

    scanline = av_malloc(bytes_per_scanline + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!scanline)
        return AVERROR(ENOMEM);

    if (nplanes == 3 && bits_per_pixel == 8) {
        for (y=0; y<h; y++) {
            pcx_rle_decode(&gb, scanline, bytes_per_scanline, compressed);

            for (x=0; x<w; x++) {
                ptr[3*x  ] = scanline[x                    ];
                ptr[3*x+1] = scanline[x+ bytes_per_line    ];
                ptr[3*x+2] = scanline[x+(bytes_per_line<<1)];
            }

            ptr += stride;
        }

    } else if (nplanes == 1 && bits_per_pixel == 8) {
        int palstart = avpkt->size - 769;

        for (y=0; y<h; y++, ptr+=stride) {
            pcx_rle_decode(&gb, scanline, bytes_per_scanline, compressed);
            memcpy(ptr, scanline, w);
        }

        if (bytestream2_tell(&gb) != palstart) {
            av_log(avctx, AV_LOG_WARNING, "image data possibly corrupted\n");
            bytestream2_seek(&gb, palstart, SEEK_SET);
        }
        if (bytestream2_get_byte(&gb) != 12) {
            av_log(avctx, AV_LOG_ERROR, "expected palette after image data\n");
            ret = AVERROR_INVALIDDATA;
            goto end;
        }

    } else if (nplanes == 1) {   /* all packed formats, max. 16 colors */
        GetBitContext s;

        for (y=0; y<h; y++) {
            init_get_bits8(&s, scanline, bytes_per_scanline);

            pcx_rle_decode(&gb, scanline, bytes_per_scanline, compressed);

            for (x=0; x<w; x++)
                ptr[x] = get_bits(&s, bits_per_pixel);
            ptr += stride;
        }

    } else {    /* planar, 4, 8 or 16 colors */
        int i;

        for (y=0; y<h; y++) {
            pcx_rle_decode(&gb, scanline, bytes_per_scanline, compressed);

            for (x=0; x<w; x++) {
                int m = 0x80 >> (x&7), v = 0;
                for (i=nplanes - 1; i>=0; i--) {
                    v <<= 1;
                    v  += !!(scanline[i*bytes_per_line + (x>>3)] & m);
                }
                ptr[x] = v;
            }
            ptr += stride;
        }
    }

    ret = bytestream2_tell(&gb);
    if (nplanes == 1 && bits_per_pixel == 8) {
        pcx_palette(&gb, (uint32_t *) p->data[1], 256);
        ret += 256 * 3;
    } else if (bits_per_pixel * nplanes == 1) {
        AV_WN32A(p->data[1]  , 0xFF000000);
        AV_WN32A(p->data[1]+4, 0xFFFFFFFF);
    } else if (bits_per_pixel < 8) {
        bytestream2_seek(&gb, 16, SEEK_SET);
        pcx_palette(&gb, (uint32_t *) p->data[1], 16);
    }

    *got_frame = 1;

end:
    av_free(scanline);
    return ret;
}

AVCodec ff_pcx_decoder = {
    .name           = "pcx",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_PCX,
    .decode         = pcx_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("PC Paintbrush PCX image"),
};