porting png support from -f image to -f image2

Originally committed as revision 3665 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 943 insertions, 0 deletions

diff --git a/libavcodec/png.c b/libavcodec/png.c
new file mode 100644
index 0000000000..079795ab9d
--- /dev/null
+++ b/libavcodec/png.c
@@ -0,0 +1,943 @@
+/*
+ * PNG image format
+ * Copyright (c) 2003 Fabrice Bellard.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "avcodec.h"
+
+/* TODO:
+ * - add 2, 4 and 16 bit depth support
+ * - use filters when generating a png (better compression)
+ */
+
+#ifdef CONFIG_ZLIB
+#include <zlib.h>
+
+//#define DEBUG
+
+#define PNG_COLOR_MASK_PALETTE    1
+#define PNG_COLOR_MASK_COLOR      2
+#define PNG_COLOR_MASK_ALPHA      4
+
+#define PNG_COLOR_TYPE_GRAY 0
+#define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
+#define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
+#define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
+#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
+
+#define PNG_FILTER_VALUE_NONE  0
+#define PNG_FILTER_VALUE_SUB   1
+#define PNG_FILTER_VALUE_UP    2
+#define PNG_FILTER_VALUE_AVG   3
+#define PNG_FILTER_VALUE_PAETH 4
+
+#define PNG_IHDR      0x0001
+#define PNG_IDAT      0x0002
+#define PNG_ALLIMAGE  0x0004
+#define PNG_PLTE      0x0008
+
+#define NB_PASSES 7
+
+#define IOBUF_SIZE 4096
+
+typedef struct PNGContext {
+    uint8_t *bytestream;
+    uint8_t *bytestream_start;
+    uint8_t *bytestream_end;
+    AVFrame picture;
+
+    int state;
+    int width, height;
+    int bit_depth;
+    int color_type;
+    int compression_type;
+    int interlace_type;
+    int filter_type;
+    int channels;
+    int bits_per_pixel;
+    int bpp;
+    
+    uint8_t *image_buf;
+    int image_linesize;
+    uint32_t palette[256];
+    uint8_t *crow_buf;
+    uint8_t *last_row;
+    uint8_t *tmp_row;
+    int pass;
+    int crow_size; /* compressed row size (include filter type) */
+    int row_size; /* decompressed row size */
+    int pass_row_size; /* decompress row size of the current pass */
+    int y;
+    z_stream zstream;
+    uint8_t buf[IOBUF_SIZE];
+} PNGContext;
+
+static unsigned int get32(uint8_t **b){
+    (*b) += 4;
+    return ((*b)[-4]<<24) + ((*b)[-3]<<16) + ((*b)[-2]<<8) + (*b)[-1];
+}
+
+static void put32(uint8_t **b, unsigned int v){
+    *(*b)++= v>>24;
+    *(*b)++= v>>16;
+    *(*b)++= v>>8;
+    *(*b)++= v;
+}
+
+static const uint8_t pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+
+/* Mask to determine which y pixels are valid in a pass */
+static const uint8_t png_pass_ymask[NB_PASSES] = {
+    0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55,
+};
+
+/* 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,
+};
+
+/* minimum x value */
+static const uint8_t png_pass_xmin[NB_PASSES] = {
+    0, 4, 0, 2, 0, 1, 0
+};
+
+/* x shift to get row width */
+static const uint8_t png_pass_xshift[NB_PASSES] = {
+    3, 3, 2, 2, 1, 1, 0
+};
+
+/* Mask to determine which pixels are valid in a pass */
+static const uint8_t png_pass_mask[NB_PASSES] = {
+    0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff
+};
+
+/* 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
+};
+#if 0
+static int png_probe(AVProbeData *pd)
+{
+    if (pd->buf_size >= 8 &&
+        memcmp(pd->buf, pngsig, 8) == 0)
+        return AVPROBE_SCORE_MAX;
+    else
+        return 0;
+}
+#endif
+static void *png_zalloc(void *opaque, unsigned int items, unsigned int size)
+{
+    return av_malloc(items * size);
+}
+
+static void png_zfree(void *opaque, void *ptr)
+{
+    av_free(ptr);
+}
+
+static int png_get_nb_channels(int color_type)
+{
+    int channels;
+    channels = 1;
+    if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) ==
+        PNG_COLOR_MASK_COLOR)
+        channels = 3;
+    if (color_type & PNG_COLOR_MASK_ALPHA)
+        channels++;
+    return channels;
+}
+
+/* compute the row size of an interleaved pass */
+static int png_pass_row_size(int pass, int bits_per_pixel, int width)
+{
+    int shift, xmin, pass_width;
+
+    xmin = png_pass_xmin[pass];
+    if (width <= xmin)
+        return 0;
+    shift = png_pass_xshift[pass];
+    pass_width = (width - xmin + (1 << shift) - 1) >> shift;
+    return (pass_width * bits_per_pixel + 7) >> 3;
+}
+
+/* NOTE: we try to construct a good looking image at each pass. width
+   is the original image width. We also do pixel format convertion 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 = png_pass_mask[pass];
+    dsp_mask = png_pass_dsp_mask[pass];
+    switch(bits_per_pixel) {
+    case 1:
+        /* we must intialize 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;
+    }
+}
+
+static void png_get_interlaced_row(uint8_t *dst, int row_size, 
+                                   int bits_per_pixel, int pass, 
+                                   const uint8_t *src, int width)
+{
+    int x, mask, dst_x, j, b, bpp;
+    uint8_t *d;
+    const uint8_t *s;
+
+    mask = png_pass_mask[pass];
+    switch(bits_per_pixel) {
+    case 1:
+        memset(dst, 0, row_size);
+        dst_x = 0;
+        for(x = 0; x < width; x++) {
+            j = (x & 7);
+            if ((mask << j) & 0x80) {
+                b = (src[x >> 3] >> (7 - j)) & 1;
+                dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
+                dst_x++;
+            }
+        }
+        break;
+    default:
+        bpp = bits_per_pixel >> 3;
+        d = dst;
+        s = src;
+        for(x = 0; x < width; x++) {
+            j = x & 7;
+            if ((mask << j) & 0x80) {
+                memcpy(d, s, bpp);
+                d += bpp;
+            }
+            s += bpp;
+        }
+        break;
+    }
+}
+
+/* XXX: optimize */
+/* NOTE: 'dst' can be equal to 'last' */
+static void png_filter_row(uint8_t *dst, int filter_type, 
+                           uint8_t *src, uint8_t *last, int size, int bpp)
+{
+    int i, p;
+
+    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];
+        }
+        for(i = bpp; i < size; i++) {
+            p = dst[i - bpp];
+            dst[i] = p + src[i];
+        }
+        break;
+    case PNG_FILTER_VALUE_UP:
+        for(i = 0; i < size; i++) {
+            p = last[i];
+            dst[i] = p + src[i];
+        }
+        break;
+    case PNG_FILTER_VALUE_AVG:
+        for(i = 0; i < bpp; i++) {
+            p = (last[i] >> 1);
+            dst[i] = p + src[i];
+        }
+        for(i = bpp; i < size; i++) {
+            p = ((dst[i - bpp] + last[i]) >> 1);
+            dst[i] = p + src[i];
+        }
+        break;
+    case PNG_FILTER_VALUE_PAETH:
+        for(i = 0; i < bpp; i++) {
+            p = last[i];
+            dst[i] = p + src[i];
+        }
+        for(i = bpp; i < size; i++) {
+            int a, b, c, pa, pb, pc;
+
+            a = dst[i - bpp];
+            b = last[i];
+            c = last[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];
+        }
+        break;
+    }
+}
+
+static void convert_from_rgba32(uint8_t *dst, const uint8_t *src, int width)
+{
+    uint8_t *d;
+    int j;
+    unsigned int v;
+    
+    d = dst;
+    for(j = 0; j < width; j++) {
+        v = ((uint32_t *)src)[j];
+        d[0] = v >> 16;
+        d[1] = v >> 8;
+        d[2] = v;
+        d[3] = v >> 24;
+        d += 4;
+    }
+}
+
+static void convert_to_rgba32(uint8_t *dst, const uint8_t *src, int width)
+{
+    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];
+        *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
+        dst += 4;
+        src += 4;
+    }
+}
+
+/* process exactly one decompressed row */
+static void png_handle_row(PNGContext *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->tmp_row, s->crow_buf[0], s->crow_buf + 1, 
+                           s->last_row, s->row_size, s->bpp);
+            memcpy(s->last_row, s->tmp_row, s->row_size);
+            convert_to_rgba32(ptr, s->tmp_row, s->width);
+        } 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(ptr, s->crow_buf[0], s->crow_buf + 1, 
+                           last_row, s->row_size, s->bpp);
+        }
+        s->y++;
+        if (s->y == s->height) {
+            s->state |= PNG_ALLIMAGE;
+        }
+    } else {
+        got_line = 0;
+        for(;;) {
+            ptr = s->image_buf + s->image_linesize * s->y;
+            if ((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->tmp_row, s->crow_buf[0], s->crow_buf + 1, 
+                               s->last_row, s->pass_row_size, s->bpp);
+                memcpy(s->last_row, s->tmp_row, s->pass_row_size);
+                got_line = 1;
+            }
+            if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
+                /* NOTE: rgba32 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 = 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(PNGContext *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,
+                        uint8_t *buf, int buf_size)
+{
+    PNGContext * const s = avctx->priv_data;
+    AVFrame *picture = data;
+    AVFrame * const p= (AVFrame*)&s->picture;
+    uint32_t tag, length;
+    int ret, crc;
+
+    /* special case for last picture */
+    if (buf_size == 0) {
+        return 0;
+    }
+    
+    s->bytestream_start=
+    s->bytestream= buf;
+    s->bytestream_end= buf + buf_size;
+
+    /* check signature */
+    if (memcmp(s->bytestream, pngsig, 8) != 0)
+        return -1;
+    s->bytestream+= 8;
+    s->y=
+    s->state=0;
+//    memset(s, 0, sizeof(PNGContext));
+    /* init the zlib */
+    s->zstream.zalloc = png_zalloc;
+    s->zstream.zfree = png_zfree;
+    s->zstream.opaque = NULL;
+    ret = inflateInit(&s->zstream);
+    if (ret != Z_OK)
+        return -1;
+    for(;;) {
+        if (s->bytestream >= s->bytestream_end)
+            goto fail;
+        length = get32(&s->bytestream);
+        if (length > 0x7fffffff)
+            goto fail;
+        tag = bswap_32(get32(&s->bytestream));
+#ifdef DEBUG
+        printf("png: tag=%c%c%c%c length=%u\n", 
+               (tag & 0xff),
+               ((tag >> 8) & 0xff),
+               ((tag >> 16) & 0xff),
+               ((tag >> 24) & 0xff), length);
+#endif
+        switch(tag) {
+        case MKTAG('I', 'H', 'D', 'R'):
+            if (length != 13)
+                goto fail;
+            s->width = get32(&s->bytestream);
+            s->height = get32(&s->bytestream);
+            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 = get32(&s->bytestream);
+            s->state |= PNG_IHDR;
+#ifdef DEBUG
+            printf("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);
+#endif
+            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 = 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_RGBA32;
+                } else if (s->bit_depth == 8 && 
+                           s->color_type == PNG_COLOR_TYPE_GRAY) {
+                    avctx->pix_fmt = PIX_FMT_GRAY8;
+                } else if (s->bit_depth == 1 && 
+                           s->color_type == PNG_COLOR_TYPE_GRAY) {
+                    avctx->pix_fmt = PIX_FMT_MONOBLACK;
+                } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
+                    avctx->pix_fmt = PIX_FMT_PAL8;
+                } 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= FF_I_TYPE;
+                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 = png_pass_row_size(s->pass, 
+                                                         s->bits_per_pixel, 
+                                                         s->width);
+                    s->crow_size = s->pass_row_size + 1;
+                }
+#ifdef DEBUG
+                printf("row_size=%d crow_size =%d\n", 
+                       s->row_size, s->crow_size);
+#endif
+                s->image_buf = p->data[0];
+                s->image_linesize = p->linesize[0];
+                /* copy the palette if needed */
+                if (s->color_type == PNG_COLOR_TYPE_PALETTE)
+                    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 */
+                s->crow_buf = av_malloc(s->row_size + 1);
+                if (!s->crow_buf)
+                    goto fail;
+                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 = get32(&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 = get32(&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 = get32(&s->bytestream);
+            }
+            break;
+        case MKTAG('I', 'E', 'N', 'D'):
+            if (!(s->state & PNG_ALLIMAGE))
+                goto fail;
+            crc = get32(&s->bytestream);
+            goto exit_loop;
+        default:
+            /* skip tag */
+        skip_tag:
+            s->bytestream += length + 4;
+            break;
+        }
+    }
+ exit_loop:
+    *picture= *(AVFrame*)&s->picture;
+    *data_size = sizeof(AVPicture);
+
+    ret = s->bytestream - s->bytestream_start;
+ the_end:
+    inflateEnd(&s->zstream);
+    av_freep(&s->crow_buf);
+    av_freep(&s->last_row);
+    av_freep(&s->tmp_row);
+    return ret;
+ fail:
+    ret = -1;
+    goto the_end;
+}
+
+static void png_write_chunk(uint8_t **f, uint32_t tag,
+                            const uint8_t *buf, int length)
+{
+    uint32_t crc;
+    uint8_t tagbuf[4];
+
+    put32(f, length);
+    crc = crc32(0, Z_NULL, 0);
+    tagbuf[0] = tag;
+    tagbuf[1] = tag >> 8;
+    tagbuf[2] = tag >> 16;
+    tagbuf[3] = tag >> 24;
+    crc = crc32(crc, tagbuf, 4);
+    put32(f, bswap_32(tag));
+    if (length > 0) {
+        crc = crc32(crc, buf, length);
+        memcpy(*f, buf, length);
+        *f += length;
+    }
+    put32(f, crc);
+}
+
+/* XXX: use avcodec generic function ? */
+static void to_be32(uint8_t *p, uint32_t v)
+{
+    p[0] = v >> 24;
+    p[1] = v >> 16;
+    p[2] = v >> 8;
+    p[3] = v;
+}
+
+/* XXX: do filtering */
+static int png_write_row(PNGContext *s, const uint8_t *data, int size)
+{
+    int ret;
+
+    s->zstream.avail_in = size;
+    s->zstream.next_in = (uint8_t *)data;
+    while (s->zstream.avail_in > 0) {
+        ret = deflate(&s->zstream, Z_NO_FLUSH);
+        if (ret != Z_OK)
+            return -1;
+        if (s->zstream.avail_out == 0) {
+            png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
+            s->zstream.avail_out = IOBUF_SIZE;
+            s->zstream.next_out = s->buf;
+        }
+    }
+    return 0;
+}
+
+static int common_init(AVCodecContext *avctx){
+    PNGContext *s = avctx->priv_data;
+
+    avcodec_get_frame_defaults((AVFrame*)&s->picture);
+    avctx->coded_frame= (AVFrame*)&s->picture;
+//    s->avctx= avctx;
+
+    return 0;
+}
+
+static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
+    PNGContext *s = avctx->priv_data;
+    AVFrame *pict = data;
+    AVFrame * const p= (AVFrame*)&s->picture;
+    int bit_depth, color_type, y, len, row_size, ret, is_progressive;
+    int bits_per_pixel, pass_row_size;
+    uint8_t *ptr;
+    uint8_t *crow_buf = NULL;
+    uint8_t *tmp_buf = NULL;
+
+    *p = *pict;
+    p->pict_type= FF_I_TYPE;
+    p->key_frame= 1;
+    
+    s->bytestream_start=
+    s->bytestream= buf;
+    s->bytestream_end= buf+buf_size;
+
+    is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
+    switch(avctx->pix_fmt) {
+    case PIX_FMT_RGBA32:
+        bit_depth = 8;
+        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+        break;
+    case PIX_FMT_RGB24:
+        bit_depth = 8;
+        color_type = PNG_COLOR_TYPE_RGB;
+        break;
+    case PIX_FMT_GRAY8:
+        bit_depth = 8;
+        color_type = PNG_COLOR_TYPE_GRAY;
+        break;
+    case PIX_FMT_MONOBLACK:
+        bit_depth = 1;
+        color_type = PNG_COLOR_TYPE_GRAY;
+        break;
+    case PIX_FMT_PAL8:
+        bit_depth = 8;
+        color_type = PNG_COLOR_TYPE_PALETTE;
+        break;
+    default:
+        return -1;
+    }
+    bits_per_pixel = png_get_nb_channels(color_type) * bit_depth;
+    row_size = (avctx->width * bits_per_pixel + 7) >> 3;
+
+    s->zstream.zalloc = png_zalloc;
+    s->zstream.zfree = png_zfree;
+    s->zstream.opaque = NULL;
+    ret = deflateInit2(&s->zstream, Z_DEFAULT_COMPRESSION,
+                       Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
+    if (ret != Z_OK)
+        return -1;
+    crow_buf = av_malloc(row_size + 1);
+    if (!crow_buf)
+        goto fail;
+    if (is_progressive) {
+        tmp_buf = av_malloc(row_size + 1);
+        if (!tmp_buf)
+            goto fail;
+    }
+
+    /* write png header */
+    memcpy(s->bytestream, pngsig, 8);
+    s->bytestream += 8;
+    
+    to_be32(s->buf, avctx->width);
+    to_be32(s->buf + 4, avctx->height);
+    s->buf[8] = bit_depth;
+    s->buf[9] = color_type;
+    s->buf[10] = 0; /* compression type */
+    s->buf[11] = 0; /* filter type */
+    s->buf[12] = is_progressive; /* interlace type */
+    
+    png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
+
+    /* put the palette if needed */
+    if (color_type == PNG_COLOR_TYPE_PALETTE) {
+        int has_alpha, alpha, i;
+        unsigned int v;
+        uint32_t *palette;
+        uint8_t *alpha_ptr;
+        
+        palette = (uint32_t *)p->data[1];
+        ptr = s->buf;
+        alpha_ptr = s->buf + 256 * 3;
+        has_alpha = 0;
+        for(i = 0; i < 256; i++) {
+            v = palette[i];
+            alpha = v >> 24;
+            if (alpha != 0xff)
+                has_alpha = 1;
+            *alpha_ptr++ = alpha;
+            ptr[0] = v >> 16;
+            ptr[1] = v >> 8;
+            ptr[2] = v;
+            ptr += 3;
+        }
+        png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
+        if (has_alpha) {
+            png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
+        }
+    }
+
+    /* now put each row */
+    s->zstream.avail_out = IOBUF_SIZE;
+    s->zstream.next_out = s->buf;
+    if (is_progressive) {
+        uint8_t *ptr1;
+        int pass;
+
+        for(pass = 0; pass < NB_PASSES; pass++) {
+            /* NOTE: a pass is completely omited if no pixels would be
+               output */
+            pass_row_size = png_pass_row_size(pass, bits_per_pixel, avctx->width);
+            if (pass_row_size > 0) {
+                for(y = 0; y < avctx->height; y++) {
+                    if ((png_pass_ymask[pass] << (y & 7)) & 0x80) {
+                        ptr = p->data[0] + y * p->linesize[0];
+                        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
+                            convert_from_rgba32(tmp_buf, ptr, avctx->width);
+                            ptr1 = tmp_buf;
+                        } else {
+                            ptr1 = ptr;
+                        }
+                        png_get_interlaced_row(crow_buf + 1, pass_row_size, 
+                                               bits_per_pixel, pass, 
+                                               ptr1, avctx->width);
+                        crow_buf[0] = PNG_FILTER_VALUE_NONE;
+                        png_write_row(s, crow_buf, pass_row_size + 1);
+                    }
+                }
+            }
+        }
+    } else {
+        for(y = 0; y < avctx->height; y++) {
+            ptr = p->data[0] + y * p->linesize[0];
+            if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+                convert_from_rgba32(crow_buf + 1, ptr, avctx->width);
+            else
+                memcpy(crow_buf + 1, ptr, row_size);
+            crow_buf[0] = PNG_FILTER_VALUE_NONE;
+            png_write_row(s, crow_buf, row_size + 1);
+        }
+    }
+    /* compress last bytes */
+    for(;;) {
+        ret = deflate(&s->zstream, Z_FINISH);
+        if (ret == Z_OK || ret == Z_STREAM_END) {
+            len = IOBUF_SIZE - s->zstream.avail_out;
+            if (len > 0) {
+                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
+            }
+            s->zstream.avail_out = IOBUF_SIZE;
+            s->zstream.next_out = s->buf;
+            if (ret == Z_STREAM_END)
+                break;
+        } else {
+            goto fail;
+        }
+    }
+    png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
+
+    ret = s->bytestream - s->bytestream_start;
+ the_end:
+    av_free(crow_buf);
+    av_free(tmp_buf);
+    deflateEnd(&s->zstream);
+    return ret;
+ fail:
+    ret = -1;
+    goto the_end;
+}
+
+AVCodec png_decoder = {
+    "png",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_PNG,
+    sizeof(PNGContext),
+    common_init,
+    NULL,
+    NULL, //decode_end,
+    decode_frame,
+    0 /*CODEC_CAP_DR1*/ /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
+    NULL
+};
+
+AVCodec png_encoder = {
+    "png",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_PNG,
+    sizeof(PNGContext),
+    common_init,
+    encode_frame,
+    NULL, //encode_end,
+    .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGBA32, PIX_FMT_PAL8, PIX_FMT_GRAY8, PIX_FMT_MONOBLACK, -1},
+};
+#endif