diff options
author | Baptiste Coudurier <baptiste.coudurier@gmail.com> | 2009-12-03 22:17:39 +0300 |
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committer | Baptiste Coudurier <baptiste.coudurier@gmail.com> | 2009-12-03 22:17:39 +0300 |
commit | f38e450746ca52c7965146ebdbcdd4cc30ad1fd9 (patch) | |
tree | 0473d3dfd69f930f3baaf12564256343bf132bf6 /libavcodec/gif.c | |
parent | b10fa1bb8b9d4074b1d4dd7364ca236a574c9951 (diff) |
use lzw compression in gif encoder
Originally committed as revision 20723 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/gif.c')
-rw-r--r-- | libavcodec/gif.c | 82 |
1 files changed, 42 insertions, 40 deletions
diff --git a/libavcodec/gif.c b/libavcodec/gif.c index fae1366e01..8c7f72ba80 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)"), }; |