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use lzw compression in gif encoder

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Originally committed as revision 20723 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Baptiste Coudurier 2009-12-03 19:17:39 +00:00
parent b10fa1bb8b
commit f38e450746
4 changed files with 64 additions and 48 deletions
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80
libavcodec/gif.c
View File

@ -43,6 +43,7 @@
#include "avcodec.h"
#include "bytestream.h"
#include "lzw.h"
/* The GIF format uses reversed order for bitstreams... */
/* at least they don't use PDP_ENDIAN :) */
@ -50,11 +51,10 @@
#include "put_bits.h"
/* bitstream minipacket size */
#define GIF_CHUNKS 100
typedef struct {
AVFrame picture;
LZWState *lzw;
uint8_t *buf;
} GIFContext;
/* GIF header */
@ -82,12 +82,12 @@ static int gif_image_write_header(AVCodecContext *avctx,
return 0;
}
static int gif_image_write_image(AVCodecContext *avctx, uint8_t **bytestream,
static int gif_image_write_image(AVCodecContext *avctx,
uint8_t **bytestream, uint8_t *end,
const uint8_t *buf, int linesize)
{
PutBitContext p;
uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
int i, left, w;
GIFContext *s = avctx->priv_data;
int len, height;
const uint8_t *ptr;
/* image block */
@ -101,39 +101,25 @@ static int gif_image_write_image(AVCodecContext *avctx, uint8_t **bytestream,
bytestream_put_byte(bytestream, 0x08);
left= avctx->width * avctx->height;
ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height,
12, FF_LZW_GIF, put_bits);
init_put_bits(&p, buffer, 130);
/*
* the thing here is the bitstream is written as little packets, with a size byte before
* but it's still the same bitstream between packets (no flush !)
*/
ptr = buf;
w = avctx->width;
while(left>0) {
for (height = avctx->height; height--;) {
len += ff_lzw_encode(s->lzw, ptr, avctx->width);
ptr += linesize;
}
len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
put_bits(&p, 9, 0x0100); /* clear code */
for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
put_bits(&p, 9, *ptr++);
if (--w == 0) {
w = avctx->width;
buf += linesize;
ptr = buf;
}
}
if(left<=GIF_CHUNKS) {
put_bits(&p, 9, 0x101); /* end of stream */
flush_put_bits(&p);
}
if(put_bits_ptr(&p) - p.buf > 0) {
bytestream_put_byte(bytestream, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
bytestream_put_buffer(bytestream, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
}
left-=GIF_CHUNKS;
ptr = s->buf;
while (len > 0) {
int size = FFMIN(255, len);
bytestream_put_byte(bytestream, size);
if (end - *bytestream < size)
return -1;
bytestream_put_buffer(bytestream, ptr, size);
ptr += size;
len -= size;
}
bytestream_put_byte(bytestream, 0x00); /* end of image block */
bytestream_put_byte(bytestream, 0x3b);
@ -145,6 +131,12 @@ static av_cold int gif_encode_init(AVCodecContext *avctx)
GIFContext *s = avctx->priv_data;
avctx->coded_frame = &s->picture;
s->lzw = av_mallocz(ff_lzw_encode_state_size);
if (!s->lzw)
return AVERROR_NOMEM;
s->buf = av_malloc(avctx->width*avctx->height*2);
if (!s->buf)
return AVERROR_NOMEM;
return 0;
}
@ -155,15 +147,25 @@ static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int bu
AVFrame *pict = data;
AVFrame *const p = (AVFrame *)&s->picture;
uint8_t *outbuf_ptr = outbuf;
uint8_t *end = outbuf + buf_size;
*p = *pict;
p->pict_type = FF_I_TYPE;
p->key_frame = 1;
gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]);
gif_image_write_image(avctx, &outbuf_ptr, pict->data[0], pict->linesize[0]);
gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]);
return outbuf_ptr - outbuf;
}
static int gif_encode_close(AVCodecContext *avctx)
{
GIFContext *s = avctx->priv_data;
av_freep(&s->lzw);
av_freep(&s->buf);
return 0;
}
AVCodec gif_encoder = {
"gif",
CODEC_TYPE_VIDEO,
@ -171,7 +173,7 @@ AVCodec gif_encoder = {
sizeof(GIFContext),
gif_encode_init,
gif_encode_frame,
NULL, //encode_end,
gif_encode_close,
.pix_fmts= (const enum PixelFormat[]){PIX_FMT_RGB8, PIX_FMT_BGR8, PIX_FMT_RGB4_BYTE, PIX_FMT_BGR4_BYTE, PIX_FMT_GRAY8, PIX_FMT_PAL8, PIX_FMT_NONE},
.long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
};

9
libavcodec/lzw.h
View File

@ -32,6 +32,8 @@
#include "get_bits.h"
struct PutBitContext;
enum FF_LZW_MODES{
FF_LZW_GIF,
FF_LZW_TIFF
@ -52,8 +54,11 @@ void ff_lzw_decode_tail(LZWState *lzw);
struct LZWEncodeState;
extern const int ff_lzw_encode_state_size;
void ff_lzw_encode_init(struct LZWEncodeState * s, uint8_t * outbuf, int outsize, int maxbits);
void ff_lzw_encode_init(struct LZWEncodeState *s, uint8_t *outbuf, int outsize,
int maxbits, enum FF_LZW_MODES mode,
void (*lzw_put_bits)(struct PutBitContext *, int, unsigned int));
int ff_lzw_encode(struct LZWEncodeState * s, const uint8_t * inbuf, int insize);
int ff_lzw_encode_flush(struct LZWEncodeState * s);
int ff_lzw_encode_flush(struct LZWEncodeState *s,
void (*lzw_flush_put_bits)(struct PutBitContext *));
#endif /* AVCODEC_LZW_H */

17
libavcodec/lzwenc.c
View File

@ -58,6 +58,8 @@ typedef struct LZWEncodeState {
int maxcode; ///< Max value of code
int output_bytes; ///< Number of written bytes
int last_code; ///< Value of last output code or LZW_PREFIX_EMPTY
enum FF_LZW_MODES mode; ///< TIFF or GIF
void (*put_bits)(PutBitContext *, int, unsigned); ///< GIF is LE while TIFF is BE
}LZWEncodeState;
@ -110,7 +112,7 @@ static inline int hashOffset(const int head)
static inline void writeCode(LZWEncodeState * s, int c)
{
assert(0 <= c && c < 1 << s->bits);
put_bits(&s->pb, s->bits, c);
s->put_bits(&s->pb, s->bits, c);
}
@ -151,7 +153,7 @@ static inline void addCode(LZWEncodeState * s, uint8_t c, int hash_prefix, int h
s->tabsize++;
if (s->tabsize >= 1 << s->bits)
if (s->tabsize >= (1 << s->bits) + (s->mode == FF_LZW_GIF))
s->bits++;
}
@ -196,7 +198,9 @@ static int writtenBytes(LZWEncodeState *s){
* @param outsize Size of output buffer
* @param maxbits Maximum length of code
*/
void ff_lzw_encode_init(LZWEncodeState * s, uint8_t * outbuf, int outsize, int maxbits)
void ff_lzw_encode_init(LZWEncodeState *s, uint8_t *outbuf, int outsize,
int maxbits, enum FF_LZW_MODES mode,
void (*lzw_put_bits)(PutBitContext *, int, unsigned))
{
s->clear_code = 256;
s->end_code = 257;
@ -208,6 +212,8 @@ void ff_lzw_encode_init(LZWEncodeState * s, uint8_t * outbuf, int outsize, int m
s->output_bytes = 0;
s->last_code = LZW_PREFIX_EMPTY;
s->bits = 9;
s->mode = mode;
s->put_bits = lzw_put_bits;
}
/**
@ -250,12 +256,13 @@ int ff_lzw_encode(LZWEncodeState * s, const uint8_t * inbuf, int insize)
* @param s LZW state
* @return Number of bytes written or -1 on error
*/
int ff_lzw_encode_flush(LZWEncodeState * s)
int ff_lzw_encode_flush(LZWEncodeState *s,
void (*lzw_flush_put_bits)(PutBitContext *))
{
if (s->last_code != -1)
writeCode(s, s->last_code);
writeCode(s, s->end_code);
flush_put_bits(&s->pb);
lzw_flush_put_bits(&s->pb);
s->last_code = -1;
return writtenBytes(s);

6
libavcodec/tiffenc.c
View File

@ -32,6 +32,7 @@
#include "tiff.h"
#include "rle.h"
#include "lzw.h"
#include "put_bits.h"
#define TIFF_MAX_ENTRY 32
@ -352,7 +353,8 @@ static int encode_frame(AVCodecContext * avctx, unsigned char *buf,
for (i = 0; i < s->height; i++) {
if (strip_sizes[i / s->rps] == 0) {
if(s->compr == TIFF_LZW){
ff_lzw_encode_init(s->lzws, ptr, s->buf_size - (*s->buf - s->buf_start), 12);
ff_lzw_encode_init(s->lzws, ptr, s->buf_size - (*s->buf - s->buf_start),
12, FF_LZW_TIFF, put_bits);
}
strip_offsets[i / s->rps] = ptr - buf;
}
@ -372,7 +374,7 @@ static int encode_frame(AVCodecContext * avctx, unsigned char *buf,
ptr += n;
if(s->compr == TIFF_LZW && (i==s->height-1 || i%s->rps == s->rps-1)){
int ret;
ret = ff_lzw_encode_flush(s->lzws);
ret = ff_lzw_encode_flush(s->lzws, flush_put_bits);
strip_sizes[(i / s->rps )] += ret ;
ptr += ret;
}