PeerStreamer

/*

 * PNG image format

 * Copyright (c) 2003 Fabrice Bellard

 *

 * 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

 */

//#define DEBUG

#include "libavutil/imgutils.h"

#include "avcodec.h"

#include "bytestream.h"

#include "png.h"

/* TODO:

 * - add 2, 4 and 16 bit depth support

 */

#include <zlib.h>

/* Mask to determine which y pixels can be written in a pass */

static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {

    0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,

};

/* Mask to determine which pixels to overwrite while displaying */

static const uint8_t png_pass_dsp_mask[NB_PASSES] = {

    0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff

};

/* NOTE: we try to construct a good looking image at each pass. width

   is the original image width. We also do pixel format conversion at

   this stage */

static void png_put_interlaced_row(uint8_t *dst, int width,

                                   int bits_per_pixel, int pass,

                                   int color_type, const uint8_t *src)

{

    int x, mask, dsp_mask, j, src_x, b, bpp;

    uint8_t *d;

    const uint8_t *s;

    mask = ff_png_pass_mask[pass];

    dsp_mask = png_pass_dsp_mask[pass];

    switch(bits_per_pixel) {

    case 1:

        /* we must initialize the line to zero before writing to it */

        if (pass == 0)

            memset(dst, 0, (width + 7) >> 3);

        src_x = 0;

        for(x = 0; x < width; x++) {

            j = (x & 7);

            if ((dsp_mask << j) & 0x80) {

                b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;

                dst[x >> 3] |= b << (7 - j);

            }

            if ((mask << j) & 0x80)

                src_x++;

        }

        break;

    default:

        bpp = bits_per_pixel >> 3;

        d = dst;

        s = src;

        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {

            for(x = 0; x < width; x++) {

                j = x & 7;

                if ((dsp_mask << j) & 0x80) {

                    *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];

                }

                d += bpp;

                if ((mask << j) & 0x80)

                    s += bpp;

            }

        } else {

            for(x = 0; x < width; x++) {

                j = x & 7;

                if ((dsp_mask << j) & 0x80) {

                    memcpy(d, s, bpp);

                }

                d += bpp;

                if ((mask << j) & 0x80)

                    s += bpp;

            }

        }

        break;

    }

}

// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size

#define pb_7f (~0UL/255 * 0x7f)

#define pb_80 (~0UL/255 * 0x80)

static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)

{

    long i;

    for(i=0; i<=w-sizeof(long); i+=sizeof(long)){

        long a = *(long*)(src1+i);

        long b = *(long*)(src2+i);

        *(long*)(dst+i) = ((a&pb_7f) + (b&pb_7f)) ^ ((a^b)&pb_80);

    }

    for(; i<w; i++)

        dst[i] = src1[i]+src2[i];

}

static void add_paeth_prediction_c(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)

{

    int i;

    for(i = 0; i < w; i++) {

        int a, b, c, p, pa, pb, pc;

        a = dst[i - bpp];

        b = top[i];

        c = top[i - bpp];

        p = b - c;

        pc = a - c;

        pa = abs(p);

        pb = abs(pc);

        pc = abs(p + pc);

        if (pa <= pb && pa <= pc)

            p = a;

        else if (pb <= pc)

            p = b;

        else

            p = c;

        dst[i] = p + src[i];

    }

}

#define UNROLL1(bpp, op) {\

                 r = dst[0];\

    if(bpp >= 2) g = dst[1];\

    if(bpp >= 3) b = dst[2];\

    if(bpp >= 4) a = dst[3];\

    for(; i < size; i+=bpp) {\

        dst[i+0] = r = op(r, src[i+0], last[i+0]);\

        if(bpp == 1) continue;\

        dst[i+1] = g = op(g, src[i+1], last[i+1]);\

        if(bpp == 2) continue;\

        dst[i+2] = b = op(b, src[i+2], last[i+2]);\

        if(bpp == 3) continue;\

        dst[i+3] = a = op(a, src[i+3], last[i+3]);\

    }\

}

#define UNROLL_FILTER(op)\

         if(bpp == 1) UNROLL1(1, op)\

    else if(bpp == 2) UNROLL1(2, op)\

    else if(bpp == 3) UNROLL1(3, op)\

    else if(bpp == 4) UNROLL1(4, op)\

    else {\

        for (; i < size; i += bpp) {\

            int j;\

            for (j = 0; j < bpp; j++)\

                dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\

        }\

    }

/* NOTE: 'dst' can be equal to 'last' */

static void png_filter_row(PNGDecContext *s, uint8_t *dst, int filter_type,

                           uint8_t *src, uint8_t *last, int size, int bpp)

{

    int i, p, r, g, b, a;

    switch(filter_type) {

    case PNG_FILTER_VALUE_NONE:

        memcpy(dst, src, size);

        break;

    case PNG_FILTER_VALUE_SUB:

        for(i = 0; i < bpp; i++) {

            dst[i] = src[i];

        }

        if(bpp == 4) {

            p = *(int*)dst;

            for(; i < size; i+=bpp) {

                int s = *(int*)(src+i);

                p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);

                *(int*)(dst+i) = p;

            }

        } else {

#define OP_SUB(x,s,l) x+s

            UNROLL_FILTER(OP_SUB);

        }

        break;

    case PNG_FILTER_VALUE_UP:

        s->add_bytes_l2(dst, src, last, size);

        break;

    case PNG_FILTER_VALUE_AVG:

        for(i = 0; i < bpp; i++) {

            p = (last[i] >> 1);

            dst[i] = p + src[i];

        }

#define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff

        UNROLL_FILTER(OP_AVG);

        break;

    case PNG_FILTER_VALUE_PAETH:

        for(i = 0; i < bpp; i++) {

            p = last[i];

            dst[i] = p + src[i];

        }

        if(bpp > 1 && size > 4) {

            // would write off the end of the array if we let it process the last pixel with bpp=3

            int w = bpp==4 ? size : size-3;

            s->add_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);

            i = w;

        }

        add_paeth_prediction_c(dst+i, src+i, last+i, size-i, bpp);

        break;

    }

}

static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)

{

    int j;

    unsigned int r, g, b, a;

    for(j = 0;j < width; j++) {

        r = src[0];

        g = src[1];

        b = src[2];

        a = src[3];

        if(loco) {

            r = (r+g)&0xff;

            b = (b+g)&0xff;

        }

        *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;

        dst += 4;

        src += 4;

    }

}

static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)

{

    if(loco)

        convert_to_rgb32_loco(dst, src, width, 1);

    else

        convert_to_rgb32_loco(dst, src, width, 0);

}

static void deloco_rgb24(uint8_t *dst, int size)

{

    int i;

    for(i=0; i<size; i+=3) {

        int g = dst[i+1];

        dst[i+0] += g;

        dst[i+2] += g;

    }

}

/* process exactly one decompressed row */

static void png_handle_row(PNGDecContext *s)

{

    uint8_t *ptr, *last_row;

    int got_line;

    if (!s->interlace_type) {

        ptr = s->image_buf + s->image_linesize * s->y;

        /* need to swap bytes correctly for RGB_ALPHA */

        if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {

            png_filter_row(s, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,

                           s->last_row, s->row_size, s->bpp);

            convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);

            FFSWAP(uint8_t*, s->last_row, s->tmp_row);

        } else {

            /* in normal case, we avoid one copy */

            if (s->y == 0)

                last_row = s->last_row;

            else

                last_row = ptr - s->image_linesize;

            png_filter_row(s, ptr, s->crow_buf[0], s->crow_buf + 1,

                           last_row, s->row_size, s->bpp);

        }

        /* loco lags by 1 row so that it doesn't interfere with top prediction */

        if (s->filter_type == PNG_FILTER_TYPE_LOCO &&

            s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)

            deloco_rgb24(ptr - s->image_linesize, s->row_size);

        s->y++;

        if (s->y == s->height) {

            s->state |= PNG_ALLIMAGE;

            if (s->filter_type == PNG_FILTER_TYPE_LOCO &&

                s->color_type == PNG_COLOR_TYPE_RGB)

                deloco_rgb24(ptr, s->row_size);

        }

    } else {

        got_line = 0;

        for(;;) {

            ptr = s->image_buf + s->image_linesize * s->y;

            if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {

                /* if we already read one row, it is time to stop to

                   wait for the next one */

                if (got_line)

                    break;

                png_filter_row(s, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,

                               s->last_row, s->pass_row_size, s->bpp);

                FFSWAP(uint8_t*, s->last_row, s->tmp_row);

                got_line = 1;

            }

            if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {

                /* NOTE: RGB32 is handled directly in png_put_interlaced_row */

                png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,

                                       s->color_type, s->last_row);

            }

            s->y++;

            if (s->y == s->height) {

                for(;;) {

                    if (s->pass == NB_PASSES - 1) {

                        s->state |= PNG_ALLIMAGE;

                        goto the_end;

                    } else {

                        s->pass++;

                        s->y = 0;

                        s->pass_row_size = ff_png_pass_row_size(s->pass,

                                                             s->bits_per_pixel,

                                                             s->width);

                        s->crow_size = s->pass_row_size + 1;

                        if (s->pass_row_size != 0)

                            break;

                        /* skip pass if empty row */

                    }

                }

            }

        }

    the_end: ;

    }

}

static int png_decode_idat(PNGDecContext *s, int length)

{

    int ret;

    s->zstream.avail_in = length;

    s->zstream.next_in = s->bytestream;

    s->bytestream += length;

    if(s->bytestream > s->bytestream_end)

        return -1;

    /* decode one line if possible */

    while (s->zstream.avail_in > 0) {

        ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);

        if (ret != Z_OK && ret != Z_STREAM_END) {

            return -1;

        }

        if (s->zstream.avail_out == 0) {

            if (!(s->state & PNG_ALLIMAGE)) {

                png_handle_row(s);

            }

            s->zstream.avail_out = s->crow_size;

            s->zstream.next_out = s->crow_buf;

        }

    }

    return 0;

}

static int decode_frame(AVCodecContext *avctx,

                        void *data, int *data_size,

                        AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    PNGDecContext * const s = avctx->priv_data;

    AVFrame *picture = data;

    AVFrame *p;

    uint8_t *crow_buf_base = NULL;

    uint32_t tag, length;

    int ret, crc;

    FFSWAP(AVFrame *, s->current_picture, s->last_picture);

    avctx->coded_frame= s->current_picture;

    p = s->current_picture;

    s->bytestream_start=

    s->bytestream= buf;

    s->bytestream_end= buf + buf_size;

    /* check signature */

    if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&

        memcmp(s->bytestream, ff_mngsig, 8) != 0)

        return -1;

    s->bytestream+= 8;

    s->y=

    s->state=0;

//    memset(s, 0, sizeof(PNGDecContext));

    /* init the zlib */

    s->zstream.zalloc = ff_png_zalloc;

    s->zstream.zfree = ff_png_zfree;

    s->zstream.opaque = NULL;

    ret = inflateInit(&s->zstream);

    if (ret != Z_OK)

        return -1;

    for(;;) {

        int tag32;

        if (s->bytestream >= s->bytestream_end)

            goto fail;

        length = bytestream_get_be32(&s->bytestream);

        if (length > 0x7fffffff)

            goto fail;

        tag32 = bytestream_get_be32(&s->bytestream);

        tag = av_bswap32(tag32);

        av_dlog(avctx, "png: tag=%c%c%c%c length=%u\n",

                (tag & 0xff),

                ((tag >> 8) & 0xff),

                ((tag >> 16) & 0xff),

                ((tag >> 24) & 0xff), length);

        switch(tag) {

        case MKTAG('I', 'H', 'D', 'R'):

            if (length != 13)

                goto fail;

            s->width = bytestream_get_be32(&s->bytestream);

            s->height = bytestream_get_be32(&s->bytestream);

            if(av_image_check_size(s->width, s->height, 0, avctx)){

                s->width= s->height= 0;

                goto fail;

            }

            s->bit_depth = *s->bytestream++;

            s->color_type = *s->bytestream++;

            s->compression_type = *s->bytestream++;

            s->filter_type = *s->bytestream++;

            s->interlace_type = *s->bytestream++;

            crc = bytestream_get_be32(&s->bytestream);

            s->state |= PNG_IHDR;

            av_dlog(avctx, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",

                    s->width, s->height, s->bit_depth, s->color_type,

                    s->compression_type, s->filter_type, s->interlace_type);

            break;

        case MKTAG('I', 'D', 'A', 'T'):

            if (!(s->state & PNG_IHDR))

                goto fail;

            if (!(s->state & PNG_IDAT)) {

                /* init image info */

                avctx->width = s->width;

                avctx->height = s->height;

                s->channels = ff_png_get_nb_channels(s->color_type);

                s->bits_per_pixel = s->bit_depth * s->channels;

                s->bpp = (s->bits_per_pixel + 7) >> 3;

                s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;

                if (s->bit_depth == 8 &&

                    s->color_type == PNG_COLOR_TYPE_RGB) {

                    avctx->pix_fmt = PIX_FMT_RGB24;

                } else if (s->bit_depth == 8 &&

                           s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {

                    avctx->pix_fmt = PIX_FMT_RGB32;

                } else if (s->bit_depth == 8 &&

                           s->color_type == PNG_COLOR_TYPE_GRAY) {

                    avctx->pix_fmt = PIX_FMT_GRAY8;

                } else if (s->bit_depth == 16 &&

                           s->color_type == PNG_COLOR_TYPE_GRAY) {

                    avctx->pix_fmt = PIX_FMT_GRAY16BE;

                } else if (s->bit_depth == 16 &&

                           s->color_type == PNG_COLOR_TYPE_RGB) {

                    avctx->pix_fmt = PIX_FMT_RGB48BE;

                } else if (s->bit_depth == 1) {

                    avctx->pix_fmt = PIX_FMT_MONOBLACK;

                } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {

                    avctx->pix_fmt = PIX_FMT_PAL8;

                } else if (s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {

                    avctx->pix_fmt = PIX_FMT_GRAY8A;

                } else {

                    goto fail;

                }

                if(p->data[0])

                    avctx->release_buffer(avctx, p);

                p->reference= 0;

                if(avctx->get_buffer(avctx, p) < 0){

                    av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

                    goto fail;

                }

                p->pict_type= AV_PICTURE_TYPE_I;

                p->key_frame= 1;

                p->interlaced_frame = !!s->interlace_type;

                /* compute the compressed row size */

                if (!s->interlace_type) {

                    s->crow_size = s->row_size + 1;

                } else {

                    s->pass = 0;

                    s->pass_row_size = ff_png_pass_row_size(s->pass,

                                                         s->bits_per_pixel,

                                                         s->width);

                    s->crow_size = s->pass_row_size + 1;

                }

                av_dlog(avctx, "row_size=%d crow_size =%d\n",

                        s->row_size, s->crow_size);

                s->image_buf = p->data[0];

                s->image_linesize = p->linesize[0];

                /* copy the palette if needed */

                if (avctx->pix_fmt == PIX_FMT_PAL8)

                    memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));

                /* empty row is used if differencing to the first row */

                s->last_row = av_mallocz(s->row_size);

                if (!s->last_row)

                    goto fail;

                if (s->interlace_type ||

                    s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {

                    s->tmp_row = av_malloc(s->row_size);

                    if (!s->tmp_row)

                        goto fail;

                }

                /* compressed row */

                crow_buf_base = av_malloc(s->row_size + 16);

                if (!crow_buf_base)

                    goto fail;

                /* we want crow_buf+1 to be 16-byte aligned */

                s->crow_buf = crow_buf_base + 15;

                s->zstream.avail_out = s->crow_size;

                s->zstream.next_out = s->crow_buf;

            }

            s->state |= PNG_IDAT;

            if (png_decode_idat(s, length) < 0)

                goto fail;

            /* skip crc */

            crc = bytestream_get_be32(&s->bytestream);

            break;

        case MKTAG('P', 'L', 'T', 'E'):

            {

                int n, i, r, g, b;

                if ((length % 3) != 0 || length > 256 * 3)

                    goto skip_tag;

                /* read the palette */

                n = length / 3;

                for(i=0;i<n;i++) {

                    r = *s->bytestream++;

                    g = *s->bytestream++;

                    b = *s->bytestream++;

                    s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;

                }

                for(;i<256;i++) {

                    s->palette[i] = (0xff << 24);

                }

                s->state |= PNG_PLTE;

                crc = bytestream_get_be32(&s->bytestream);

            }

            break;

        case MKTAG('t', 'R', 'N', 'S'):

            {

                int v, i;

                /* read the transparency. XXX: Only palette mode supported */

                if (s->color_type != PNG_COLOR_TYPE_PALETTE ||

                    length > 256 ||

                    !(s->state & PNG_PLTE))

                    goto skip_tag;

                for(i=0;i<length;i++) {

                    v = *s->bytestream++;

                    s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);

                }

                crc = bytestream_get_be32(&s->bytestream);

            }

            break;

        case MKTAG('I', 'E', 'N', 'D'):

            if (!(s->state & PNG_ALLIMAGE))

                goto fail;

            crc = bytestream_get_be32(&s->bytestream);

            goto exit_loop;

        default:

            /* skip tag */

        skip_tag:

            s->bytestream += length + 4;

            break;

        }

    }

 exit_loop:

     /* handle p-frames only if a predecessor frame is available */

     if(s->last_picture->data[0] != NULL) {

         if(!(avpkt->flags & AV_PKT_FLAG_KEY)) {

            int i, j;

            uint8_t *pd = s->current_picture->data[0];

            uint8_t *pd_last = s->last_picture->data[0];

            for(j=0; j < s->height; j++) {

                for(i=0; i < s->width * s->bpp; i++) {

                    pd[i] += pd_last[i];

                }

                pd += s->image_linesize;

                pd_last += s->image_linesize;

            }

        }

    }

    *picture= *s->current_picture;

    *data_size = sizeof(AVFrame);

    ret = s->bytestream - s->bytestream_start;

 the_end:

    inflateEnd(&s->zstream);

    av_free(crow_buf_base);

    s->crow_buf = NULL;

    av_freep(&s->last_row);

    av_freep(&s->tmp_row);

    return ret;

 fail:

    ret = -1;

    goto the_end;

}

static av_cold int png_dec_init(AVCodecContext *avctx)

{

    PNGDecContext *s = avctx->priv_data;

    s->current_picture = &s->picture1;

    s->last_picture = &s->picture2;

    avcodec_get_frame_defaults(&s->picture1);

    avcodec_get_frame_defaults(&s->picture2);

#if HAVE_MMX

    ff_png_init_mmx(s);

#endif

    if (!s->add_paeth_prediction)

        s->add_paeth_prediction = add_paeth_prediction_c;

    if (!s->add_bytes_l2)

        s->add_bytes_l2 = add_bytes_l2_c;

    return 0;

}

static av_cold int png_dec_end(AVCodecContext *avctx)

{

    PNGDecContext *s = avctx->priv_data;

    if (s->picture1.data[0])

        avctx->release_buffer(avctx, &s->picture1);

    if (s->picture2.data[0])

        avctx->release_buffer(avctx, &s->picture2);

    return 0;

}

AVCodec ff_png_decoder = {

    "png",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_PNG,

    sizeof(PNGDecContext),

    png_dec_init,

    NULL,

    png_dec_end,

    decode_frame,

    CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,

    NULL,

    .long_name = NULL_IF_CONFIG_SMALL("PNG image"),

};