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png filters
Originally committed as revision 12195 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Loren Merritt
parent
e281d6844b
commit
4a5b619df7
@ -39,6 +39,7 @@
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#define PNG_FILTER_VALUE_UP 2
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#define PNG_FILTER_VALUE_AVG 3
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#define PNG_FILTER_VALUE_PAETH 4
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#define PNG_FILTER_VALUE_MIXED 5
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#define PNG_IHDR 0x0001
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#define PNG_IDAT 0x0002
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@ -21,10 +21,10 @@
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#include "avcodec.h"
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#include "bytestream.h"
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#include "png.h"
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#include <dsputil.h>
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/* TODO:
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* - add 2, 4 and 16 bit depth support
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* - use filters when generating a png (better compression)
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*/
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#include <zlib.h>
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@ -34,11 +34,15 @@
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#define IOBUF_SIZE 4096
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typedef struct PNGEncContext {
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DSPContext dsp;
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uint8_t *bytestream;
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uint8_t *bytestream_start;
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uint8_t *bytestream_end;
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AVFrame picture;
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int filter_type;
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z_stream zstream;
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uint8_t buf[IOBUF_SIZE];
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} PNGEncContext;
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@ -81,6 +85,93 @@ static void png_get_interlaced_row(uint8_t *dst, int row_size,
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}
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}
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static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
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{
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int i;
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for(i = 0; i < w; i++) {
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int a, b, c, p, pa, pb, pc;
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a = src[i - bpp];
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b = top[i];
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c = top[i - bpp];
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p = b - c;
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pc = a - c;
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pa = abs(p);
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pb = abs(pc);
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pc = abs(p + pc);
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if (pa <= pb && pa <= pc)
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p = a;
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else if (pb <= pc)
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p = b;
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else
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p = c;
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dst[i] = src[i] - p;
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}
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}
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static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
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uint8_t *src, uint8_t *top, int size, int bpp)
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{
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int i;
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switch(filter_type) {
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case PNG_FILTER_VALUE_NONE:
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memcpy(dst, src, size);
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break;
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case PNG_FILTER_VALUE_SUB:
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dsp->diff_bytes(dst, src, src-bpp, size);
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memcpy(dst, src, bpp);
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break;
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case PNG_FILTER_VALUE_UP:
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dsp->diff_bytes(dst, src, top, size);
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break;
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case PNG_FILTER_VALUE_AVG:
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for(i = 0; i < bpp; i++)
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dst[i] = src[i] - (top[i] >> 1);
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for(; i < size; i++)
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dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
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break;
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case PNG_FILTER_VALUE_PAETH:
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for(i = 0; i < bpp; i++)
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dst[i] = src[i] - top[i];
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sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
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break;
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}
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}
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static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
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uint8_t *src, uint8_t *top, int size, int bpp)
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{
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int pred = s->filter_type;
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assert(bpp || !pred);
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if(!top && pred)
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pred = PNG_FILTER_VALUE_SUB;
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if(pred == PNG_FILTER_VALUE_MIXED) {
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int i;
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int cost, bcost = INT_MAX;
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uint8_t *buf1 = dst, *buf2 = dst + size + 16;
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for(pred=0; pred<5; pred++) {
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png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
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buf1[0] = pred;
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cost = 0;
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for(i=0; i<=size; i++)
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cost += abs(0x80 - (buf1[i] ^ 0x80));
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if(cost < bcost) {
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bcost = cost;
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FFSWAP(uint8_t*, buf1, buf2);
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}
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}
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return buf2;
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} else {
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png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
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dst[0] = pred;
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return dst;
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}
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}
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static void convert_from_rgb32(uint8_t *dst, const uint8_t *src, int width)
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{
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uint8_t *d;
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@ -145,9 +236,11 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size,
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int bit_depth, color_type, y, len, row_size, ret, is_progressive;
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int bits_per_pixel, pass_row_size;
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int compression_level;
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uint8_t *ptr;
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uint8_t *crow_buf = NULL;
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uint8_t *tmp_buf = NULL;
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uint8_t *ptr, *top;
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uint8_t *crow_base = NULL, *crow_buf, *crow;
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uint8_t *progressive_buf = NULL;
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uint8_t *rgba_buf = NULL;
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uint8_t *top_buf = NULL;
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*p = *pict;
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p->pict_type= FF_I_TYPE;
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@ -195,12 +288,23 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size,
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Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
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if (ret != Z_OK)
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return -1;
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crow_buf = av_malloc(row_size + 1);
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if (!crow_buf)
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crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
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if (!crow_base)
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goto fail;
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crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
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if (is_progressive) {
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tmp_buf = av_malloc(row_size + 1);
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if (!tmp_buf)
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progressive_buf = av_malloc(row_size + 1);
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if (!progressive_buf)
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goto fail;
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}
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
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rgba_buf = av_malloc(row_size + 1);
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if (!rgba_buf)
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goto fail;
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}
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if (is_progressive || color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
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top_buf = av_malloc(row_size + 1);
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if (!top_buf)
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goto fail;
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}
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@ -247,7 +351,6 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size,
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s->zstream.avail_out = IOBUF_SIZE;
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s->zstream.next_out = s->buf;
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if (is_progressive) {
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uint8_t *ptr1;
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int pass;
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for(pass = 0; pass < NB_PASSES; pass++) {
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@ -255,33 +358,37 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size,
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output */
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pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
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if (pass_row_size > 0) {
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top = NULL;
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for(y = 0; y < avctx->height; y++) {
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if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
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ptr = p->data[0] + y * p->linesize[0];
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FFSWAP(uint8_t*, progressive_buf, top_buf);
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
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convert_from_rgb32(tmp_buf, ptr, avctx->width);
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ptr1 = tmp_buf;
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} else {
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ptr1 = ptr;
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convert_from_rgb32(rgba_buf, ptr, avctx->width);
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ptr = rgba_buf;
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}
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png_get_interlaced_row(crow_buf + 1, pass_row_size,
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png_get_interlaced_row(progressive_buf, pass_row_size,
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bits_per_pixel, pass,
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ptr1, avctx->width);
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crow_buf[0] = PNG_FILTER_VALUE_NONE;
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png_write_row(s, crow_buf, pass_row_size + 1);
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ptr, avctx->width);
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crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
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png_write_row(s, crow, pass_row_size + 1);
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top = progressive_buf;
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}
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}
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}
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}
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} else {
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top = NULL;
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for(y = 0; y < avctx->height; y++) {
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ptr = p->data[0] + y * p->linesize[0];
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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convert_from_rgb32(crow_buf + 1, ptr, avctx->width);
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else
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memcpy(crow_buf + 1, ptr, row_size);
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crow_buf[0] = PNG_FILTER_VALUE_NONE;
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png_write_row(s, crow_buf, row_size + 1);
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
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FFSWAP(uint8_t*, rgba_buf, top_buf);
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convert_from_rgb32(rgba_buf, ptr, avctx->width);
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ptr = rgba_buf;
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}
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crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
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png_write_row(s, crow, row_size + 1);
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top = ptr;
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}
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}
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/* compress last bytes */
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@ -304,8 +411,10 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size,
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ret = s->bytestream - s->bytestream_start;
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the_end:
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av_free(crow_buf);
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av_free(tmp_buf);
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av_free(crow_base);
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av_free(progressive_buf);
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av_free(rgba_buf);
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av_free(top_buf);
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deflateEnd(&s->zstream);
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return ret;
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fail:
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@ -318,6 +427,11 @@ static int png_enc_init(AVCodecContext *avctx){
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avcodec_get_frame_defaults((AVFrame*)&s->picture);
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avctx->coded_frame= (AVFrame*)&s->picture;
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dsputil_init(&s->dsp, avctx);
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s->filter_type = av_clip(avctx->prediction_method, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED);
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if(avctx->pix_fmt == PIX_FMT_MONOBLACK)
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s->filter_type = PNG_FILTER_VALUE_NONE;
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return 0;
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}
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