[FFmpeg-devel] [PATCH] CCITT Group 3 and 4 decompression

Kostya kostya.shishkov
Tue Dec 23 08:00:57 CET 2008


On Mon, Dec 22, 2008 at 09:06:37PM +0100, Michael Niedermayer wrote:
> On Mon, Dec 22, 2008 at 08:15:06PM +0200, Kostya wrote:
> > On Mon, Dec 22, 2008 at 01:13:53PM +0100, Michael Niedermayer wrote:
> > > On Mon, Dec 22, 2008 at 08:31:55AM +0200, Kostya wrote:
> > > > I need that for resolving issue 750 on roundup.
[...]
> > +{
> > +    static VLC_TYPE code_table1[528][2];
> > +    static VLC_TYPE code_table2[648][2];
> > +    int i;
> > +    if(ccitt_group3_2d_vlc.table)
> > +        return;
> 
> this is not thread safe, this is not the last value written.
> 
> and yes these functions can be called from several threads from
> av_find_stream_info() ...
> alternative solutions are welcome as well but as long as av_find_stream_info
> does what it does all init must be thread safe.
 
now it should be thread safe

[...]
> 
> > +static inline int decode_group3_1d_line(AVCodecContext *avctx, GetBitContext *gb,
> > +                                        int pix_left, int *runs)
> > +{
> > +    int mode = 0, run = 0, t;
> > +    while(pix_left){
> > +        t = get_vlc2(gb, ccitt_vlc[mode].table, 9, 2);
> > +        run += t;
> > +        if(t == -1){
> > +            av_log(avctx, AV_LOG_ERROR, "Incorrect code @ %d\n",avctx->width -pix_left);
> > +            return -1;
> > +        }
> > +        if(t >= 64)
> > +            continue;
> > +        pix_left -= run;
> > +        if(pix_left < 0){
> > +            av_log(avctx, AV_LOG_ERROR, "Run went out of bounds\n");
> > +            return -1;
> > +        }
> > +        *runs++ = run;
> > +        run = 0;
> > +        mode = !mode;
> > +    }
> > +    *runs++ = 0;
> > +    return 0;
> > +}
> 
> This still has 4 ifs on the most commonly excuted path, the code i provided
> has 2, is there any reason why you do not use something based on just 2?

Your code was wrong since it could not check for incorrect code (t = -1 was
falling into t<64 condition). 

> And just the clarify, the "continue" path can only be executed once every
> 64 pixels and thus is of less relevance speedwise.

?
no, it's not a counter. For example, white run of 2000 pixels will be coded
as two values: <1984><16>. See ITU T.4
 
> also the code can end in a "infinite" and then segfaulting loop through the
> continue

Probably not. When bitreader is out of data it will return zeroes and there's no
all-zero code in the list, so get_vlc2() will return -1 eventually.

> > +
> > +static inline int decode_group3_2d_line(AVCodecContext *avctx, GetBitContext *gb,
> > +                                        int pix_left, int *runs, const int *ref)
> > +{
> 
> the function does not look speed critical enough for the inline ...
> 
> 
> [...]
> 
> > +
> > +static void put_line(uint8_t *dst, int size, int width, const int *runs)
> > +{
> > +    PutBitContext pb;
> > +    int run, t, mode = 0, pix_left = width;
> > +
> > +    init_put_bits(&pb, dst, size*8);
> > +    while(pix_left > 0){
> > +        run = *runs++;
> > +        pix_left -= run;
> 
> > +        while(run){
> > +            t = FFMIN(run, 16);
> > +            put_sbits(&pb, t, -mode);
> > +            run -= t;
> > +        }
> 
> for(; run>=16; run-=16)
>     put_sbits(&pb, 16, -mode);
> put_sbits(&pb, run, -mode);
> 
> 
> [...]
> > +int ff_ccitt_unpack_group3_1d(AVCodecContext *avctx,
> > +                              const uint8_t *src, int srcsize,
> > +                              uint8_t *dst, int height, int stride, int padded)
> > +{
> > +    int j;
> > +    GetBitContext gb;
> > +    int *runs;
> > +
> > +    runs = av_malloc(avctx->width * sizeof(runs[0]));
> > +    init_get_bits(&gb, src, srcsize*8);
> > +    for(j = 0; j < height; j++){
> > +        if(padded){
> > +            int bits = get_bits_count(&gb) & 7;
> > +            if(bits != 4)
> > +                skip_bits(&gb, (12 - bits) & 7);
> > +        }
> > +        if(get_bits(&gb, 12) != 1){
> > +            av_log(avctx, AV_LOG_ERROR, "EOL syncmarker not found, resyncing\n");
> > +            do{
> > +                skip_bits1(&gb);
> > +            }while(get_bits_count(&gb) < srcsize*8 && show_bits(&gb, 12) != 1);
> > +            if(get_bits_count(&gb) >= srcsize*8)
> > +                return -1;
> > +        }
> 
> how is this supposed to work?
> once a line is damaged and lost there can be 1 line less thus this can
> still run out of data and fail.

it's the question of what to do with damaged data 
 
> [...]
> > +int ff_ccitt_unpack_group3_2d(AVCodecContext *avctx,
> > +                              const uint8_t *src, int srcsize,
> > +                              uint8_t *dst, int height, int stride, int padded)
> > +{
> > +    int j;
> > +    GetBitContext gb;
> > +    int *runs, *ref;
> > +    int ret;
> > +
> > +    runs = av_malloc((avctx->width + 1) * sizeof(runs[0]));
> > +    ref  = av_malloc((avctx->width + 1) * sizeof(ref[0]));
> > +    runs[0] = 0;
> > +    ref[0] = 0;
> > +    ref[1] = avctx->width;
> > +    init_get_bits(&gb, src, srcsize*8);
> > +    for(j = 0; j < height; j++){
> 
> > +        if(padded){
> > +            int bits = get_bits_count(&gb) & 7;
> > +            if(bits != 4)
> > +                skip_bits(&gb, (12 - bits) & 7);
> > +        }
> > +        if(get_bits(&gb, 12) != 1){
> > +            av_log(avctx, AV_LOG_ERROR, "EOL syncmarker not found, resyncing\n");
> > +            do{
> > +                skip_bits1(&gb);
> > +            }while(get_bits_count(&gb) < srcsize*8 && show_bits(&gb, 12) != 1);
> > +            if(get_bits_count(&gb) >= srcsize*8)
> > +                return -1;
> > +        }
> 
> duplicate

factorized out
 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
-------------- next part --------------
Index: libavcodec/Makefile
===================================================================
--- libavcodec/Makefile	(revision 15993)
+++ libavcodec/Makefile	(working copy)
@@ -201,7 +201,7 @@
 OBJS-$(CONFIG_THEORA_DECODER)          += vp3.o xiph.o vp3dsp.o
 OBJS-$(CONFIG_THP_DECODER)             += mjpegdec.o mjpeg.o
 OBJS-$(CONFIG_TIERTEXSEQVIDEO_DECODER) += tiertexseqv.o
-OBJS-$(CONFIG_TIFF_DECODER)            += tiff.o lzw.o
+OBJS-$(CONFIG_TIFF_DECODER)            += tiff.o lzw.o faxcompr.o
 OBJS-$(CONFIG_TIFF_ENCODER)            += tiffenc.o rle.o lzwenc.o
 OBJS-$(CONFIG_TRUEMOTION1_DECODER)     += truemotion1.o
 OBJS-$(CONFIG_TRUEMOTION2_DECODER)     += truemotion2.o
Index: libavcodec/tiff.c
===================================================================
--- libavcodec/tiff.c	(revision 16268)
+++ libavcodec/tiff.c	(working copy)
@@ -30,6 +30,7 @@
 #endif
 #include "lzw.h"
 #include "tiff.h"
+#include "faxcompr.h"
 
 
 typedef struct TiffContext {
@@ -41,6 +42,7 @@
     int le;
     int compr;
     int invert;
+    int fax_opts;
     int predictor;
 
     int strips, rps, sstype;
@@ -103,6 +105,29 @@
             return -1;
         }
     }
+    if(s->compr == TIFF_CCITT_RLE || s->compr == TIFF_G3 || s->compr == TIFF_G4){
+        int i, ret = 0;
+        uint8_t *src2;
+
+        src2 = av_malloc(size);
+        for(i = 0; i < size; i++)
+            src2[i] = ff_reverse[src[i]];
+        if(s->compr == TIFF_G3 && !(s->fax_opts & 1))
+            s->compr = TIFF_CCITT_RLE;
+        switch(s->compr){
+        case TIFF_CCITT_RLE:
+            ret = ff_ccitt_unpack_group3_1d(s->avctx, src2, size, dst, lines, stride);
+            break;
+        case TIFF_G3:
+            ret = ff_ccitt_unpack_group3_2d(s->avctx, src2, size, dst, lines, stride);
+            break;
+        case TIFF_G4:
+            ret = ff_ccitt_unpack_group4   (s->avctx, src2, size, dst, lines, stride);
+            break;
+        }
+        av_free(src2);
+        return ret;
+    }
     for(line = 0; line < lines; line++){
         if(src - ssrc > size){
             av_log(s->avctx, AV_LOG_ERROR, "Source data overread\n");
@@ -265,7 +290,12 @@
         case TIFF_RAW:
         case TIFF_PACKBITS:
         case TIFF_LZW:
+        case TIFF_CCITT_RLE:
             break;
+        case TIFF_G3:
+        case TIFF_G4:
+            s->fax_opts = 0;
+            break;
         case TIFF_DEFLATE:
         case TIFF_ADOBE_DEFLATE:
 #ifdef CONFIG_ZLIB
@@ -274,15 +304,6 @@
             av_log(s->avctx, AV_LOG_ERROR, "Deflate: ZLib not compiled in\n");
             return -1;
 #endif
-        case TIFF_G3:
-            av_log(s->avctx, AV_LOG_ERROR, "CCITT G3 compression is not supported\n");
-            return -1;
-        case TIFF_G4:
-            av_log(s->avctx, AV_LOG_ERROR, "CCITT G4 compression is not supported\n");
-            return -1;
-        case TIFF_CCITT_RLE:
-            av_log(s->avctx, AV_LOG_ERROR, "CCITT RLE compression is not supported\n");
-            return -1;
         case TIFF_JPEG:
         case TIFF_NEWJPEG:
             av_log(s->avctx, AV_LOG_ERROR, "JPEG compression is not supported\n");
@@ -373,6 +394,10 @@
             return -1;
         }
         break;
+    case TIFF_T4OPTIONS:
+    case TIFF_T6OPTIONS:
+        s->fax_opts = value;
+        break;
     }
     return 0;
 }
@@ -487,6 +512,7 @@
     avctx->coded_frame= (AVFrame*)&s->picture;
     s->picture.data[0] = NULL;
     ff_lzw_decode_open(&s->lzw);
+    ff_ccitt_unpack_init();
 
     return 0;
 }
Index: libavcodec/faxcompr.h
===================================================================
--- libavcodec/faxcompr.h	(revision 0)
+++ libavcodec/faxcompr.h	(revision 0)
@@ -0,0 +1,58 @@
+/*
+ * CCITT Fax Group 3 and 4 decompression
+ * Copyright (c) 2008 Konstantin Shishkov
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * CCITT Fax Group 3 and 4 decompression
+ * @file faxcompr.h
+ * @author Konstantin Shishkov
+ */
+#ifndef AVCODEC_FAXCOMPR_H
+#define AVCODEC_FAXCOMPR_H
+
+#include "avcodec.h"
+
+/**
+ * initialize upacker code
+ */
+void ff_ccitt_unpack_init();
+
+/**
+ * unpack data compressed with CCITT Group 3 1-D method
+ */
+int ff_ccitt_unpack_group3_1d(AVCodecContext *avctx,
+                              const uint8_t *src, int srcsize,
+                              uint8_t *dst, int height, int stride);
+
+/**
+ * unpack data compressed with CCITT Group 3 2-D method
+ */
+int ff_ccitt_unpack_group3_2d(AVCodecContext *avctx,
+                              const uint8_t *src, int srcsize,
+                              uint8_t *dst, int height, int stride);
+
+/**
+ * unpack data compressed with CCITT Group 4 1-D method
+ */
+int ff_ccitt_unpack_group4(AVCodecContext *avctx,
+                           const uint8_t *src, int srcsize,
+                           uint8_t *dst, int height, int stride);
+
+#endif /* AVCODEC_FAXCOMPR_H */
Index: libavcodec/faxcompr.c
===================================================================
--- libavcodec/faxcompr.c	(revision 0)
+++ libavcodec/faxcompr.c	(revision 0)
@@ -0,0 +1,338 @@
+/*
+ * CCITT Fax Group 3 and 4 decompression
+ * Copyright (c) 2008 Konstantin Shishkov
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * CCITT Fax Group 3 and 4 decompression
+ * @file faxcompr.c
+ * @author Konstantin Shishkov
+ */
+#include "avcodec.h"
+#include "bitstream.h"
+#include "faxcompr.h"
+
+#define CCITT_SYMS 104
+
+static const uint16_t ccitt_syms[CCITT_SYMS] = {
+    0,    1,    2,    3,    4,    5,    6,    7,    8,    9,   10,   11,   12,
+   13,   14,   15,   16,   17,   18,   19,   20,   21,   22,   23,   24,   25,
+   26,   27,   28,   29,   30,   31,   32,   33,   34,   35,   36,   37,   38,
+   39,   40,   41,   42,   43,   44,   45,   46,   47,   48,   49,   50,   51,
+   52,   53,   54,   55,   56,   57,   58,   59,   60,   61,   62,   63,   64,
+  128,  192,  256,  320,  384,  448,  512,  576,  640,  704,  768,  832,  896,
+  960, 1024, 1088, 1152, 1216, 1280, 1344, 1408, 1472, 1536, 1600, 1664, 1728,
+ 1792, 1856, 1920, 1984, 2048, 2112, 2176, 2240, 2304, 2368, 2432, 2496, 2560
+};
+
+static const uint8_t ccitt_codes_bits[2][CCITT_SYMS] =
+{
+  {
+    0x35, 0x07, 0x07, 0x08, 0x0B, 0x0C, 0x0E, 0x0F, 0x13, 0x14, 0x07, 0x08, 0x08,
+    0x03, 0x34, 0x35, 0x2A, 0x2B, 0x27, 0x0C, 0x08, 0x17, 0x03, 0x04, 0x28, 0x2B,
+    0x13, 0x24, 0x18, 0x02, 0x03, 0x1A, 0x1B, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+    0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x04, 0x05, 0x0A, 0x0B, 0x52, 0x53, 0x54,
+    0x55, 0x24, 0x25, 0x58, 0x59, 0x5A, 0x5B, 0x4A, 0x4B, 0x32, 0x33, 0x34, 0x1B,
+    0x12, 0x17, 0x37, 0x36, 0x37, 0x64, 0x65, 0x68, 0x67, 0xCC, 0xCD, 0xD2, 0xD3,
+    0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0x98, 0x99, 0x9A, 0x18, 0x9B,
+    0x08, 0x0C, 0x0D, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x1C, 0x1D, 0x1E, 0x1F
+  },
+  {
+    0x37, 0x02, 0x03, 0x02, 0x03, 0x03, 0x02, 0x03, 0x05, 0x04, 0x04, 0x05, 0x07,
+    0x04, 0x07, 0x18, 0x17, 0x18, 0x08, 0x67, 0x68, 0x6C, 0x37, 0x28, 0x17, 0x18,
+    0xCA, 0xCB, 0xCC, 0xCD, 0x68, 0x69, 0x6A, 0x6B, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6,
+    0xD7, 0x6C, 0x6D, 0xDA, 0xDB, 0x54, 0x55, 0x56, 0x57, 0x64, 0x65, 0x52, 0x53,
+    0x24, 0x37, 0x38, 0x27, 0x28, 0x58, 0x59, 0x2B, 0x2C, 0x5A, 0x66, 0x67, 0x0F,
+    0xC8, 0xC9, 0x5B, 0x33, 0x34, 0x35, 0x6C, 0x6D, 0x4A, 0x4B, 0x4C, 0x4D, 0x72,
+    0x73, 0x74, 0x75, 0x76, 0x77, 0x52, 0x53, 0x54, 0x55, 0x5A, 0x5B, 0x64, 0x65,
+    0x08, 0x0C, 0x0D, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x1C, 0x1D, 0x1E, 0x1F
+  }
+};
+
+static const uint8_t ccitt_codes_lens[2][CCITT_SYMS] =
+{
+  {
+     8,  6,  4,  4,  4,  4,  4,  4,  5,  5,  5,  5,  6,  6,  6,  6,  6,  6,  7,  7,
+     7,  7,  7,  7,  7,  7,  7,  7,  7,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,
+     8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,
+     8,  8,  8,  8,  5,  5,  6,  7,  8,  8,  8,  8,  8,  8,  9,  9,  9,  9,  9,  9,
+     9,  9,  9,  9,  9,  9,  9,  9,  9,  6,  9, 11, 11, 11, 12, 12, 12, 12, 12, 12,
+    12, 12, 12, 12
+  },
+  {
+    10,  3,  2,  2,  3,  4,  4,  5,  6,  6,  7,  7,  7,  8,  8,  9, 10, 10, 10, 11,
+    11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+    12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+    12, 12, 12, 12, 10, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 11, 11, 11, 12, 12, 12, 12, 12, 12,
+    12, 12, 12, 12
+  }
+};
+
+static const uint8_t ccitt_group3_2d_bits[11] = {
+    1, 1, 2, 2, 2, 1, 3, 3, 3, 1, 1
+};
+
+static const uint8_t ccitt_group3_2d_lens[11] = {
+    4, 3, 7, 6, 3, 1, 3, 6, 7, 7, 9
+};
+
+static VLC ccitt_vlc[2], ccitt_group3_2d_vlc;
+
+av_cold void ff_ccitt_unpack_init()
+{
+    static VLC_TYPE code_table1[528][2];
+    static VLC_TYPE code_table2[648][2];
+    int i;
+    static int initialized = 0;
+
+    if(initialized)
+        return;
+    ccitt_vlc[0].table = code_table1;
+    ccitt_vlc[0].table_allocated = 528;
+    ccitt_vlc[1].table = code_table2;
+    ccitt_vlc[1].table_allocated = 648;
+    for(i = 0; i < 2; i++){
+        init_vlc_sparse(&ccitt_vlc[i], 9, CCITT_SYMS,
+                        ccitt_codes_lens[i], 1, 1,
+                        ccitt_codes_bits[i], 1, 1, 
+                        ccitt_syms, 2, 2,
+                        INIT_VLC_USE_NEW_STATIC);
+    }
+    INIT_VLC_STATIC(&ccitt_group3_2d_vlc, 9, 11,
+                    ccitt_group3_2d_lens, 1, 1,
+                    ccitt_group3_2d_bits, 1, 1, 512);
+    initialized = 1;
+}
+
+
+static int decode_group3_1d_line(AVCodecContext *avctx, GetBitContext *gb,
+                                 int pix_left, int *runs)
+{
+    int mode = 0, run = 0, t;
+    while(pix_left){
+        t = get_vlc2(gb, ccitt_vlc[mode].table, 9, 2);
+        run += t;
+        if(t == -1){
+            av_log(avctx, AV_LOG_ERROR, "Incorrect code\n");
+            return -1;
+        }
+        if(t >= 64)
+            continue;
+        pix_left -= run;
+        if(pix_left < 0){
+            av_log(avctx, AV_LOG_ERROR, "Run went out of bounds\n");
+            return -1;
+        }
+        *runs++ = run;
+        run = 0;
+        mode = !mode;
+    }
+    *runs++ = 0;
+    return 0;
+}
+
+static int decode_group3_2d_line(AVCodecContext *avctx, GetBitContext *gb,
+                                 int pix_left, int *runs, const int *ref)
+{
+    int mode = 0, offs = 0, run = 0, saved_run = 0, t;
+    int run_off = 0;
+
+    while(pix_left > 0){
+        int cmode = get_vlc2(gb, ccitt_group3_2d_vlc.table, 9, 1);
+        //sync line pointers
+        while(run_off <= offs && run_off < avctx->width){
+            run_off += *ref++;
+            run_off += *ref++;
+        }
+        if(cmode == -1){
+            av_log(avctx, AV_LOG_ERROR, "Incorrect mode VLC\n");
+            return -1;
+        }
+        if(!cmode){//pass mode
+            run_off += *ref++;
+            run = run_off - offs;
+            run_off += *ref++;
+            pix_left -= run;
+            offs += run;
+            saved_run += run;
+        }else if(cmode == 1){//horizontal mode
+            int k;
+            for(k = 0; k < 2; k++){
+                run = 0;
+                for(;;){
+                    t = get_vlc2(gb, ccitt_vlc[mode].table, 9, 2);
+                    if(t == -1){
+                        av_log(avctx, AV_LOG_ERROR, "Incorrect code\n");
+                        return -1;
+                    }
+                    run += t;
+                    if(t < 64)
+                        break;
+                }
+                *runs++ = run + saved_run;
+                saved_run = 0;
+                if(pix_left < run){
+                    av_log(avctx, AV_LOG_ERROR, "Run went out of bounds\n");
+                    return -1;
+                }
+                pix_left -= run;
+                offs += run;
+                mode = !mode;
+            }
+        }else if(cmode == 9 || cmode == 10){
+            av_log(avctx, AV_LOG_ERROR, "Special modes are not supported (yet)\n");
+            return -1;
+        }else{//vertical mode
+            run = run_off - offs + (cmode - 5);
+            if(cmode >= 5)
+                run_off += *ref++;
+            else
+                run_off -= *--ref;
+            pix_left -= run;
+            offs += run;
+            *runs++ = run + saved_run;
+            saved_run = 0;
+            mode = !mode;
+        }
+    }
+    *runs++ = 0;
+    return 0;
+}
+
+static void put_line(uint8_t *dst, int size, int width, const int *runs)
+{
+    PutBitContext pb;
+    int run, mode = 0, pix_left = width;
+
+    init_put_bits(&pb, dst, size*8);
+    while(pix_left > 0){
+        run = *runs++;
+        pix_left -= run;
+        for(; run >= 16; run -= 16)
+            put_sbits(&pb, 16, -mode);
+        if(run)
+            put_sbits(&pb, run, -mode);
+        mode = !mode;
+    }
+}
+
+static int find_group3_syncmarker(GetBitContext *gb, int srcsize)
+{
+    int ret = 0;
+    while(show_bits(gb, 12) != 1){
+        skip_bits1(gb);
+        ret = 1;
+        if(get_bits_count(gb) >= srcsize)
+            return -1;
+    }
+    skip_bits(gb, 12);
+    return ret;
+}
+
+int ff_ccitt_unpack_group3_1d(AVCodecContext *avctx,
+                              const uint8_t *src, int srcsize,
+                              uint8_t *dst, int height, int stride)
+{
+    int j;
+    GetBitContext gb;
+    int *runs;
+
+    runs = av_malloc(avctx->width * sizeof(runs[0]));
+    init_get_bits(&gb, src, srcsize*8);
+    for(j = 0; j < height; j++){
+        if(find_group3_syncmarker(&gb, srcsize*8) < 0)
+            break;
+        if(decode_group3_1d_line(avctx, &gb, avctx->width, runs) < 0){
+            av_log(avctx, AV_LOG_ERROR, "Error decoding line\n");
+            continue;
+        }
+        put_line(dst, stride, avctx->width, runs);
+        dst += stride;
+    }
+    av_free(runs);
+    return 0;
+}
+
+int ff_ccitt_unpack_group3_2d(AVCodecContext *avctx,
+                              const uint8_t *src, int srcsize,
+                              uint8_t *dst, int height, int stride)
+{
+    int j;
+    GetBitContext gb;
+    int *runs, *ref;
+    int ret;
+
+    runs = av_malloc((avctx->width + 1) * sizeof(runs[0]));
+    ref  = av_malloc((avctx->width + 1) * sizeof(ref[0]));
+    runs[0] = 0;
+    ref[0] = 0;
+    ref[1] = avctx->width;
+    init_get_bits(&gb, src, srcsize*8);
+    for(j = 0; j < height; j++){
+        if(find_group3_syncmarker(&gb, srcsize*8) < 0)
+            break;
+        if(get_bits1(&gb))
+            ret = decode_group3_1d_line(avctx, &gb, avctx->width, runs + 1);
+        else
+            ret = decode_group3_2d_line(avctx, &gb, avctx->width, runs + 1, ref);
+        if(ret < 0){
+            av_free(runs);
+            av_free(ref);
+            return -1;
+        }
+        put_line(dst, stride, avctx->width, runs + 1);
+        FFSWAP(int*, runs, ref);
+        dst += stride;
+    }
+    av_free(runs);
+    av_free(ref);
+    return 0;
+}
+
+int ff_ccitt_unpack_group4(AVCodecContext *avctx,
+                           const uint8_t *src, int srcsize,
+                           uint8_t *dst, int height, int stride)
+{
+    int j;
+    GetBitContext gb;
+    int *runs, *ref;
+    int ret;
+
+    runs = av_malloc((avctx->width + 1) * sizeof(runs[0]));
+    ref  = av_malloc((avctx->width + 1) * sizeof(ref[0]));
+    runs[0] = 0;
+    ref[0] = 0;
+    ref[1] = avctx->width;
+    init_get_bits(&gb, src, srcsize*8);
+    for(j = 0; j < height; j++){
+        ret = decode_group3_2d_line(avctx, &gb, avctx->width, runs + 1, ref);
+        if(ret < 0){
+            av_free(runs);
+            av_free(ref);
+            return -1;
+        }
+        put_line(dst, stride, avctx->width, runs + 1);
+        FFSWAP(int*, runs, ref);
+        dst += stride;
+    }
+    av_free(runs);
+    av_free(ref);
+    return 0;
+}



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