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sgienc: Use a local RLE encoding function

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SGI RLE encoding is slighlty different than the one provided by rle
module (especially at high bit depth). The pixel count function however
does not change, so it is simply made library-public.
This commit is contained in:
Vittorio Giovara 2015-11-20 02:17:33 +01:00
parent 62cc8f4d79
commit 59e3f4e598
3 changed files with 54 additions and 17 deletions
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15
libavcodec/rle.c
View File

@ -22,16 +22,7 @@
#include "rle.h"
#include "libavutil/common.h"
/**
* Count up to 127 consecutive pixels which are either all the same or
* all differ from the previous and next pixels.
* @param start Pointer to the first pixel
* @param len Maximum number of pixels
* @param bpp Bytes per pixel
* @param same 1 if searching for identical pixel values. 0 for differing
* @return Number of matching consecutive pixels found
*/
static int count_pixels(const uint8_t *start, int len, int bpp, int same)
int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)
{
const uint8_t *pos;
int count = 1;
@ -63,14 +54,14 @@ int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr , int bpp, i
for(x = 0; x < w; x += count) {
/* see if we can encode the next set of pixels with RLE */
if((count = count_pixels(ptr, w-x, bpp, 1)) > 1) {
if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {
if(out + bpp + 1 > outbuf + out_size) return -1;
*out++ = (count ^ xor_rep) + add_rep;
memcpy(out, ptr, bpp);
out += bpp;
} else {
/* fall back on uncompressed */
count = count_pixels(ptr, w-x, bpp, 0);
count = ff_rle_count_pixels(ptr, w - x, bpp, 0);
if(out + bpp*count >= outbuf + out_size) return -1;
*out++ = (count ^ xor_raw) + add_raw;

11
libavcodec/rle.h
View File

@ -23,6 +23,17 @@
#include <stdint.h>
/**
* Count up to 127 consecutive pixels which are either all the same or
* all differ from the previous and next pixels.
* @param start Pointer to the first pixel
* @param len Maximum number of pixels
* @param bpp Bytes per pixel
* @param same 1 if searching for identical pixel values, 0 for differing
* @return Number of matching consecutive pixels found
*/
int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same);
/**
* RLE compress the row, with maximum size of out_size. Value before repeated bytes is (count ^ xor_rep) + add_rep.
* Value before raw bytes is (count ^ xor_raw) + add_raw.

45
libavcodec/sgienc.c
View File

@ -39,6 +39,44 @@ static av_cold int encode_init(AVCodecContext *avctx)
return 0;
}
static int sgi_rle_encode(PutByteContext *pbc, const uint8_t *src,
int w, int bpp)
{
int val, count, x, start = bytestream2_tell_p(pbc);
void (*bytestream2_put)(PutByteContext *, unsigned int);
bytestream2_put = bytestream2_put_byte;
for (x = 0; x < w; x += count) {
/* see if we can encode the next set of pixels with RLE */
count = ff_rle_count_pixels(src, w - x, bpp, 1);
if (count > 1) {
if (bytestream2_get_bytes_left_p(pbc) < bpp * 2)
return AVERROR_INVALIDDATA;
val = *src;
bytestream2_put(pbc, count);
bytestream2_put(pbc, val);
} else {
int i;
/* fall back on uncompressed */
count = ff_rle_count_pixels(src, w - x, bpp, 0);
if (bytestream2_get_bytes_left_p(pbc) < bpp * (count + 1))
return AVERROR_INVALIDDATA;
bytestream2_put(pbc, count + 0x80);
for (i = 0; i < count; i++) {
val = src[i];
bytestream2_put(pbc, val);
}
}
src += count * bpp;
}
return bytestream2_tell_p(pbc) - start;
}
static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
const AVFrame *frame, int *got_packet)
{
@ -110,7 +148,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
length = SGI_HEADER_SIZE;
if (avctx->coder_type == FF_CODER_TYPE_RAW)
length += depth * height * width;
else // assume ff_rl_encode() produces at most 2x size of input
else // assume sgi_rle_encode() produces at most 2x size of input
length += tablesize * 2 + depth * height * (2 * width + 1);
if ((ret = ff_alloc_packet(pkt, bytes_per_channel * length)) < 0) {
@ -166,15 +204,12 @@ FF_ENABLE_DEPRECATION_WARNINGS
for (x = 0; x < width; x++)
encode_buf[x] = in_buf[depth * x];
length = ff_rle_encode(pbc.buffer,
bytestream2_get_bytes_left_p(&pbc),
encode_buf, 1, width, 0, 0, 0x80, 0);
length = sgi_rle_encode(&pbc, encode_buf, width, 1);
if (length < 1) {
av_free(encode_buf);
return -1;
}
bytestream2_skip_p(&pbc, length);
bytestream2_put_be32(&tablen_pcb, length);
in_buf -= p->linesize[0];
}