[SCM] libav/experimental: use lzw compression in gif encoder
siretart at users.alioth.debian.org
siretart at users.alioth.debian.org
Sun Jun 30 16:55:28 UTC 2013
The following commit has been merged in the experimental branch:
commit f38e450746ca52c7965146ebdbcdd4cc30ad1fd9
Author: Baptiste Coudurier <baptiste.coudurier at gmail.com>
Date: Thu Dec 3 19:17:39 2009 +0000
use lzw compression in gif encoder
Originally committed as revision 20723 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/gif.c b/libavcodec/gif.c
index fae1366..8c7f72b 100644
--- a/libavcodec/gif.c
+++ b/libavcodec/gif.c
@@ -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;
-
- init_put_bits(&p, buffer, 130);
+ ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height,
+ 12, FF_LZW_GIF, put_bits);
-/*
- * 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) {
-
- 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;
+ 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);
+
+ 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)"),
};
diff --git a/libavcodec/lzw.h b/libavcodec/lzw.h
index 601d01f..bebb335 100644
--- a/libavcodec/lzw.h
+++ b/libavcodec/lzw.h
@@ -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 */
diff --git a/libavcodec/lzwenc.c b/libavcodec/lzwenc.c
index f3f6683..f8cf491 100644
--- a/libavcodec/lzwenc.c
+++ b/libavcodec/lzwenc.c
@@ -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);
diff --git a/libavcodec/tiffenc.c b/libavcodec/tiffenc.c
index 7af3914..1d6b5b0 100644
--- a/libavcodec/tiffenc.c
+++ b/libavcodec/tiffenc.c
@@ -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;
}
--
Libav/FFmpeg packaging
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