avcodec/dolby_e: use av_clip_uintp2()
[ffmpeg.git] / libavcodec / h261.c
index 6ec8de6..47bad4e 100644 (file)
 /*
- * H261 decoder
+ * H.261 common code
  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (c) 2004 Maarten Daniels
  *
- * This library is free software; you can redistribute it and/or
+ * 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 of the License, or (at your option) any later version.
+ * version 2.1 of the License, or (at your option) any later version.
  *
- * This library is distributed in the hope that it will be useful,
+ * 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 this library; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
- * @file h261.c
- * h261codec.
+ * @file
+ * H.261 codec
  */
 
-#include "common.h"
-#include "dsputil.h"
 #include "avcodec.h"
-#include "mpegvideo.h"
-#include "h261data.h"
-
-
-#define H261_MBA_VLC_BITS 9
-#define H261_MTYPE_VLC_BITS 6
-#define H261_MV_VLC_BITS 7
-#define H261_CBP_VLC_BITS 9
-#define TCOEFF_VLC_BITS 9
-
-#define MAX_MBA 33
-#define IS_FIL(a)    ((a)&MB_TYPE_H261_FIL)
-
-/**
- * H261Context
- */
-typedef struct H261Context{
-    MpegEncContext s;
-
-    int current_mba;
-    int mba_diff;
-    int mtype;
-    int current_mv_x;
-    int current_mv_y;
-    int gob_number;
-    int loop_filter;
-    int bits_left; //8 - nr of bits left of the following frame in the last byte in this frame
-    int last_bits; //bits left of the following frame in the last byte in this frame
-}H261Context;
-
-void ff_h261_loop_filter(H261Context * h){
-    MpegEncContext * const s = &h->s;
-    int i;
-    const int linesize  = s->linesize;
-    const int uvlinesize= s->uvlinesize;
-    uint8_t *dest_y = s->dest[0];
-    uint8_t *dest_cb= s->dest[1];
-    uint8_t *dest_cr= s->dest[2];
-    
-    s->dsp.h261_loop_filter(dest_y                   , linesize);
-    s->dsp.h261_loop_filter(dest_y                + 8, linesize);
-    s->dsp.h261_loop_filter(dest_y + 8 * linesize    , linesize);
-    s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
-    s->dsp.h261_loop_filter(dest_cb, uvlinesize);
-    s->dsp.h261_loop_filter(dest_cr, uvlinesize);
-}
-
-static int h261_decode_block(H261Context *h, DCTELEM *block,
-                             int n, int coded);
-static int h261_decode_mb(H261Context *h,
-                      DCTELEM block[6][64]);
-void ff_set_qscale(MpegEncContext * s, int qscale);
-
-/***********************************************/
-/* decoding */
-
-static VLC h261_mba_vlc;
-static VLC h261_mtype_vlc;
-static VLC h261_mv_vlc;
-static VLC h261_cbp_vlc;
+#include "h261.h"
 
-void init_vlc_rl(RLTable *rl);
+#define IS_FIL(a)    ((a) & MB_TYPE_H261_FIL)
 
-static void h261_decode_init_vlc(H261Context *h){
-    static int done = 0;
-
-    if(!done){
-        done = 1;
-        init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 34,
-                 h261_mba_bits, 1, 1,
-                 h261_mba_code, 1, 1);
-        init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
-                 h261_mtype_bits, 1, 1,
-                 h261_mtype_code, 1, 1);
-        init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
-                 &h261_mv_tab[0][1], 2, 1,
-                 &h261_mv_tab[0][0], 2, 1);
-        init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
-                 &h261_cbp_tab[0][1], 2, 1,
-                 &h261_cbp_tab[0][0], 2, 1);
-        init_rl(&h261_rl_tcoeff);
-        init_vlc_rl(&h261_rl_tcoeff);
-    }
-}
-
-static int h261_decode_init(AVCodecContext *avctx){
-    H261Context *h= avctx->priv_data;
-    MpegEncContext * const s = &h->s;
-
-    // set defaults
-    MPV_decode_defaults(s);
-    s->avctx = avctx;
-
-    s->width = s->avctx->width;
-    s->height = s->avctx->height;
-    s->codec_id = s->avctx->codec->id;
-
-    s->out_format = FMT_H261;
-    s->low_delay= 1;
-    avctx->pix_fmt= PIX_FMT_YUV420P;
-
-    s->codec_id= avctx->codec->id;
-
-    h261_decode_init_vlc(h);
-
-    h->bits_left = 0;
-    h->last_bits = 0;
-    
-    return 0;
-}
+uint8_t ff_h261_rl_table_store[2][2 * MAX_RUN + MAX_LEVEL + 3];
 
-/**
- * decodes the group of blocks header or slice header.
- * @return <0 if an error occured
- */
-static int h261_decode_gob_header(H261Context *h){
-    unsigned int val;
-    MpegEncContext * const s = &h->s;
-    
-    /* Check for GOB Start Code */
-    val = show_bits(&s->gb, 15);
-    if(val)
-        return -1;
-
-    /* We have a GBSC */
-    skip_bits(&s->gb, 16);
-
-    h->gob_number = get_bits(&s->gb, 4); /* GN */
-    s->qscale = get_bits(&s->gb, 5); /* GQUANT */
-
-    /* GEI */
-    while (get_bits1(&s->gb) != 0) {
-        skip_bits(&s->gb, 8);
-    }
-
-    if(s->qscale==0)
-        return -1;
-
-    // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
-    // subsequent macroblocks, MBA is the difference between the absolute addresses of
-    // the macroblock and the last transmitted macroblock.
-    h->current_mba = 0;
-    h->mba_diff = 0;
-
-    return 0;
-}
-
-/**
- * decodes the group of blocks / video packet header.
- * @return <0 if no resync found
- */
-static int ff_h261_resync(H261Context *h){
-    MpegEncContext * const s = &h->s;
-    int left, ret;
-
-    if(show_bits(&s->gb, 15)==0){
-        ret= h261_decode_gob_header(h);
-        if(ret>=0)
-            return 0;
-    }
-    //ok, its not where its supposed to be ...
-    s->gb= s->last_resync_gb;
-    align_get_bits(&s->gb);
-    left= s->gb.size_in_bits - get_bits_count(&s->gb);
-
-    for(;left>15+1+4+5; left-=8){
-        if(show_bits(&s->gb, 15)==0){
-            GetBitContext bak= s->gb;
-
-            ret= h261_decode_gob_header(h);
-            if(ret>=0)
-                return 0;
-
-            s->gb= bak;
-        }
-        skip_bits(&s->gb, 8);
-    }
-
-    return -1;
-}
-
-/**
- * decodes a skipped macroblock, called when when mba_diff > 1.
- * @return 0
- */
-static int h261_decode_mb_skipped(H261Context *h,
-                                  DCTELEM block[6][64])
-{
-    MpegEncContext * const s = &h->s;
-    int i;
-    const int xy = s->mb_x + s->mb_y * s->mb_stride;
-    s->mb_intra = 0;
-    for(i=0;i<6;i++)
-        s->block_last_index[i] = -1;
-    s->mv_dir = MV_DIR_FORWARD;
-    s->mv_type = MV_TYPE_16X16;
-    s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
-    s->mv[0][0][0] = 0;
-    s->mv[0][0][1] = 0;
-    s->mb_skiped = 1;
-    return 0;
-}
-
-static int h261_decode_mb(H261Context *h,
-                          DCTELEM block[6][64])
+static void h261_loop_filter(uint8_t *src, int stride)
 {
-    MpegEncContext * const s = &h->s;
-    int i, cbp, mv_x_diff, mv_y_diff, sign, xy;
-
-    cbp = 63;
-    // Read mba
-    do{
-        h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2)+1;
-    }
-    while( h->mba_diff == MAX_MBA + 1 ); // stuffing
-
-    if ( h->mba_diff < 0 )
-        return -1;
-
-    h->current_mba += h->mba_diff;
-
-    if ( h->current_mba > MAX_MBA )
-        return -1;
-    
-    s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
-    s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
-
-    xy = s->mb_x + s->mb_y * s->mb_stride;
-
-    ff_init_block_index(s);
-    ff_update_block_index(s);
-
-    // Read mtype
-    int old_mtype = h->mtype;
-    h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
-    h->mtype = h261_mtype_map[h->mtype];
-
-    if (IS_FIL (h->mtype))
-        h->loop_filter = 1;
-
-    // Read mquant
-    if ( IS_QUANT ( h->mtype ) ){
-        s->qscale = get_bits(&s->gb, 5);
-    }
-
-    s->mb_intra = IS_INTRA4x4(h->mtype);
-
-    // Read mv
-    if ( IS_16X16 ( h->mtype ) ){
-        // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
-        // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
-        // following three situations:
-        // 1) evaluating MVD for macroblocks 1, 12 and 23;
-        // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
-        // 3) MTYPE of the previous macroblock was not MC.
-        if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
-             ( h->mba_diff != 1) || ( !IS_16X16 ( old_mtype ) ))
-        {
-            h->current_mv_x = 0;
-            h->current_mv_y = 0;
-        }
-
-        mv_x_diff = get_vlc2(&s->gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
-        mv_x_diff = mvmap[mv_x_diff];
-
-        if(mv_x_diff != 0){
-            sign = get_bits1(&s->gb);
-
-            if(!sign)
-                mv_x_diff= -mv_x_diff;
-        }
-
-        mv_y_diff = get_vlc2(&s->gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
-        mv_y_diff = mvmap[mv_y_diff];
-
-        if(mv_y_diff != 0){
-            sign = get_bits1(&s->gb);
+    int x, y, xy, yz;
+    int temp[64];
 
-            if(!sign)
-                mv_y_diff= -mv_y_diff;
-        }
-
-        //mv's are in the range -15...15
-        if((h->current_mv_x + mv_x_diff > -16) && (h->current_mv_x + mv_x_diff < 16) )
-            h->current_mv_x += mv_x_diff;
-        else
-            h->current_mv_x += (mv_x_diff + (mv_x_diff > 0 ? -32 : 32));
-
-        if((h->current_mv_y + mv_y_diff > -16) && (h->current_mv_y + mv_y_diff < 16) )
-            h->current_mv_y += mv_y_diff;
-        else
-            h->current_mv_y += (mv_y_diff + (mv_y_diff>0 ? -32 : 32));
-    }
-
-    // Read cbp
-    if ( HAS_CBP( h->mtype ) ){
-        cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
-    }
-
-    if(s->mb_intra){
-        s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
-        goto intra;
-    }
-
-    //set motion vectors
-    s->mv_dir = MV_DIR_FORWARD;
-    s->mv_type = MV_TYPE_16X16;
-    s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
-    if(IS_16X16 ( h->mtype )){
-        s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
-        s->mv[0][0][1] = h->current_mv_y * 2;
+    for (x = 0; x < 8; x++) {
+        temp[x]         = 4 * src[x];
+        temp[x + 7 * 8] = 4 * src[x + 7 * stride];
     }
-    else{
-        h->current_mv_x = s->mv[0][0][0] = 0;
-        h->current_mv_x = s->mv[0][0][1] = 0;
-    }
-
-intra:
-    /* decode each block */
-    if(s->mb_intra || HAS_CBP(h->mtype)){
-        for (i = 0; i < 6; i++) {
-            if (h261_decode_block(h, block[i], i, cbp&32) < 0){
-                return -1;
-            }
-            cbp+=cbp;
+    for (y = 1; y < 7; y++) {
+        for (x = 0; x < 8; x++) {
+            xy       = y * stride + x;
+            yz       = y * 8      + x;
+            temp[yz] = src[xy - stride] + 2 * src[xy] + src[xy + stride];
         }
     }
 
-    /* per-MB end of slice check */
-    {
-        int v= show_bits(&s->gb, 15);
-
-        if(get_bits_count(&s->gb) + 15 > s->gb.size_in_bits){
-            v>>= get_bits_count(&s->gb) + 15 - s->gb.size_in_bits;
-        }
-
-        if(v==0){
-            return SLICE_END;
+    for (y = 0; y < 8; y++) {
+        src[y * stride]     = (temp[y * 8]     + 2) >> 2;
+        src[y * stride + 7] = (temp[y * 8 + 7] + 2) >> 2;
+        for (x = 1; x < 7; x++) {
+            xy      = y * stride + x;
+            yz      = y * 8      + x;
+            src[xy] = (temp[yz - 1] + 2 * temp[yz] + temp[yz + 1] + 8) >> 4;
         }
     }
-    return SLICE_OK;
 }
 
-/**
- * decodes a macroblock
- * @return <0 if an error occured
- */
-static int h261_decode_block(H261Context * h, DCTELEM * block,
-                             int n, int coded)
+void ff_h261_loop_filter(MpegEncContext *s)
 {
-    MpegEncContext * const s = &h->s;
-    int code, level, i, j, run;
-    RLTable *rl = &h261_rl_tcoeff;
-    const uint8_t *scan_table;
-    
-    // For the variable length encoding there are two code tables, one being used for
-    // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
-    // for all other LEVELs except the first one in INTRA blocks which is fixed length
-    // coded with 8 bits.
-    // NOTE: the two code tables only differ in one VLC so we handle that manually.
-    scan_table = s->intra_scantable.permutated;
-    if (s->mb_intra){
-        /* DC coef */
-        level = get_bits(&s->gb, 8);
-        // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
-        if((level&0x7F) == 0){
-            av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
-            return -1;
-        }
-        // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
-        if (level == 255)
-            level = 128;
-        block[0] = level;
-        i = 1;
-    }else if(coded){
-        // Run  Level   Code
-        // EOB                  Not possible for first level when cbp is available (that's why the table is different)
-        // 0    1               1s
-        // *    *               0*
-        int check = show_bits(&s->gb, 2);
-        i = 0;
-        if ( check & 0x2 ){
-            skip_bits(&s->gb, 2);
-            block[0] = ( check & 0x1 ) ? -1 : 1;
-            i = 1;
-        }
-    }else{
-        i = 0;
-    }
-    if(!coded){
-        s->block_last_index[n] = i - 1;
-        return 0;
-    }
-    for(;;){
-        code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
-        if (code < 0){
-            av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
-            return -1;
-        }
-        if (code == rl->n) {
-            /* escape */
-            // The remaining combinations of (run, level) are encoded with a 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits level.
-            run = get_bits(&s->gb, 6);
-            level = (int8_t)get_bits(&s->gb, 8);
-        }else if(code == 0){
-            break;
-        }else{
-            run = rl->table_run[code];
-            level = rl->table_level[code];
-            if (get_bits1(&s->gb))
-                level = -level;
-        }
-        i += run;
-        if (i >= 64){
-            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
-            return -1;
-        }
-        j = scan_table[i];
-        block[j] = level;
-        i++;
-    }
-    s->block_last_index[n] = i;
-    return 0;
+    H261Context *h       = (H261Context *)s;
+    const int linesize   = s->linesize;
+    const int uvlinesize = s->uvlinesize;
+    uint8_t *dest_y      = s->dest[0];
+    uint8_t *dest_cb     = s->dest[1];
+    uint8_t *dest_cr     = s->dest[2];
+
+    if (!(IS_FIL(h->mtype)))
+        return;
+
+    h261_loop_filter(dest_y,                    linesize);
+    h261_loop_filter(dest_y + 8,                linesize);
+    h261_loop_filter(dest_y + 8 * linesize,     linesize);
+    h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
+    h261_loop_filter(dest_cb, uvlinesize);
+    h261_loop_filter(dest_cr, uvlinesize);
 }
 
-/**
- * decodes the H261 picture header.
- * @return <0 if no startcode found
- */
-int h261_decode_picture_header(H261Context *h){
-    MpegEncContext * const s = &h->s;
-    int format, i;
-    static int h261_framecounter = 0;
-    uint32_t startcode;
-    align_get_bits(&s->gb);
-
-    startcode = (h->last_bits << (12 - (8-h->bits_left))) | get_bits(&s->gb, 20-8 - (8- h->bits_left));
-
-    for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
-        startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
-
-        if(startcode == 0x10)
-            break;
-    }
-
-    if (startcode != 0x10){
-        av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
-        return -1;
-    }
-
-    /* temporal reference */
-    s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
-
-    /* PTYPE starts here */
-    skip_bits1(&s->gb); /* split screen off */
-    skip_bits1(&s->gb); /* camera  off */
-    skip_bits1(&s->gb); /* freeze picture release off */
-
-    format = get_bits1(&s->gb);
-
-    //only 2 formats possible
-    if (format == 0){//QCIF
-        s->width = 176;
-        s->height = 144;
-        s->mb_width = 11;
-        s->mb_height = 9;
-    }else{//CIF
-        s->width = 352;
-        s->height = 288;
-        s->mb_width = 22;
-        s->mb_height = 18;
-    }
-
-    s->mb_num = s->mb_width * s->mb_height;
-
-    skip_bits1(&s->gb); /* still image mode off */
-    skip_bits1(&s->gb); /* Reserved */
-
-    /* PEI */
-    while (get_bits1(&s->gb) != 0){
-        skip_bits(&s->gb, 8);
-    }
-
-    //h261 has no I-FRAMES, pass the test in MPV_frame_start in mpegvideo.c
-    if(h261_framecounter > 1)
-        s->pict_type = P_TYPE;
-    else
-        s->pict_type = I_TYPE;
-
-    h261_framecounter++;
-
-    h->gob_number = 0;
-    return 0;
-}
-
-static int h261_decode_gob(H261Context *h){
-    MpegEncContext * const s = &h->s;
-    int i;
-    
-    ff_set_qscale(s, s->qscale);
-    while(h->current_mba <= MAX_MBA)
-    {
-        int ret;
-        /* DCT & quantize */
-        s->dsp.clear_blocks(s->block[0]);
-        ret= h261_decode_mb(h, s->block);
-        if(ret<0){
-            const int xy= s->mb_x + s->mb_y*s->mb_stride;
-            if(ret==SLICE_END){
-                MPV_decode_mb(s, s->block);
-                if(h->loop_filter){
-                    ff_h261_loop_filter(h);
-                }
-                h->loop_filter = 0;
-                for(i=1; i<h->mba_diff; i++){
-                    s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
-                    s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
-                    ff_init_block_index(s);
-                    ff_update_block_index(s);
-                    s->dsp.clear_blocks(s->block[0]);
-                    ret= h261_decode_mb_skipped(h, s->block);
-                    MPV_decode_mb(s, s->block);
-                }
-                
-                return 0;
-            }else if(ret==SLICE_NOEND){
-                av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
-                return -1;
-            }
-            av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
-            return -1;
-        }
-        MPV_decode_mb(s, s->block);
-        if(h->loop_filter){
-            ff_h261_loop_filter(h);
-        }
-
-        h->loop_filter = 0;
-        for(i=1; i<h->mba_diff; i++){
-            s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
-            s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
-            ff_init_block_index(s);
-            ff_update_block_index(s);
-            s->dsp.clear_blocks(s->block[0]);
-            ret= h261_decode_mb_skipped(h, s->block);
-            MPV_decode_mb(s, s->block);
-        }
-    }
-    
-    return -1;
-}
-
-static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
-    int vop_found, i, j, bits_left, last_bits;
-    uint32_t state;
-
-    H261Context *h = avctx->priv_data;
-
-    if(h){
-        bits_left = h->bits_left;
-        last_bits = h->last_bits;
-    }
-    else{
-        bits_left = 0;
-        last_bits = 0;
-    }
-
-    vop_found= pc->frame_start_found;
-    state= pc->state;
-    if(bits_left!=0 && !vop_found)
-        state = state << (8-bits_left) | last_bits;
-    i=0;
-    if(!vop_found){
-        for(i=0; i<buf_size; i++){
-            state= (state<<8) | buf[i];
-            for(j=0; j<8; j++){
-                if(( (  (state<<j)  |  (buf[i]>>(8-j))  )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
-                    i++;
-                    vop_found=1;
-                    break;
-                }
-            }
-            if(vop_found)
-                    break;    
-        }
-    }
-    if(vop_found){
-        for(; i<buf_size; i++){
-            if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
-                state= (state<<8) | buf[i];
-            for(j=0; j<8; j++){
-                if(( (  (state<<j)  |  (buf[i]>>(8-j))  )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
-                    pc->frame_start_found=0;
-                    pc->state=-1;
-                    return i-3;
-                }
-            }
-        }
-    }
-
-    pc->frame_start_found= vop_found;
-    pc->state= state;
-    return END_NOT_FOUND;
-}
-
-static int h261_parse(AVCodecParserContext *s,
-                      AVCodecContext *avctx,
-                      uint8_t **poutbuf, int *poutbuf_size, 
-                      const uint8_t *buf, int buf_size)
-{
-    ParseContext *pc = s->priv_data;
-    int next;
-    
-    next= h261_find_frame_end(pc,avctx, buf, buf_size);
-    if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
-        *poutbuf = NULL;
-        *poutbuf_size = 0;
-        return buf_size;
-    }
-    *poutbuf = (uint8_t *)buf;
-    *poutbuf_size = buf_size;
-    return next;
-}
-
-/**
- * returns the number of bytes consumed for building the current frame
- */
-static int get_consumed_bytes(MpegEncContext *s, int buf_size){
-    int pos= (get_bits_count(&s->gb)+7)>>3;
-
-    if(s->flags&CODEC_FLAG_TRUNCATED){
-        pos -= s->parse_context.last_index;
-        if(pos<0) pos=0;// padding is not really read so this might be -1
-        return pos;
-    }else{
-        if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
-        if(pos+10>buf_size) pos=buf_size; // oops ;)
-
-        return pos;
-    }
-}
-
-static int h261_decode_frame(AVCodecContext *avctx,
-                             void *data, int *data_size,
-                             uint8_t *buf, int buf_size)
+av_cold void ff_h261_common_init(void)
 {
-    H261Context *h= avctx->priv_data;
-    MpegEncContext *s = &h->s;
-    int ret;
-    AVFrame *pict = data;
-
-#ifdef PRINT_FRAME_TIME
-uint64_t time= rdtsc();
-#endif
-#ifdef DEBUG
-    printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
-    printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
-#endif
-    s->flags= avctx->flags;
-    s->flags2= avctx->flags2;
-
-    /* no supplementary picture */
-    if (buf_size == 0) {
-        /* special case for last picture */
-        if (s->low_delay==0 && s->next_picture_ptr) {
-            *pict= *(AVFrame*)s->next_picture_ptr;
-            s->next_picture_ptr= NULL;
-
-            *data_size = sizeof(AVFrame);
-        }
-
-        return 0;
-    }
-
-    if(s->flags&CODEC_FLAG_TRUNCATED){
-        int next;
-
-        next= h261_find_frame_end(&s->parse_context,avctx, buf, buf_size);
-
-        if( ff_combine_frame(&s->parse_context, next, &buf, &buf_size) < 0 )
-            return buf_size;
-    }
-
-
-retry:
-
-    if(s->bitstream_buffer_size && buf_size<20){
-        init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
-    }else
-        init_get_bits(&s->gb, buf, buf_size*8);
-    s->bitstream_buffer_size=0;
-
-    if(!s->context_initialized){
-        if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
-            return -1;
-    }
-
-    //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
-    if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
-        int i= ff_find_unused_picture(s, 0);
-        s->current_picture_ptr= &s->picture[i];
-    }
-
-    ret = h261_decode_picture_header(h);
-
-    if(ret==FRAME_SKIPED) return get_consumed_bytes(s, buf_size);
-
-    /* skip if the header was thrashed */
-    if (ret < 0){
-        av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
-        return -1;
-    }
-
-    if (s->width != avctx->width || s->height != avctx->height){
-        ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
-        s->parse_context.buffer=0;
-        MPV_common_end(s);
-        s->parse_context= pc;
-    }
-    if (!s->context_initialized) {
-        avctx->width = s->width;
-        avctx->height = s->height;
-
-        goto retry;
-    }
-
-    // for hurry_up==5
-    s->current_picture.pict_type= s->pict_type;
-    s->current_picture.key_frame= s->pict_type == I_TYPE;
-
-    /* skip everything if we are in a hurry>=5 */
-    if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
-
-    if(MPV_frame_start(s, avctx) < 0)
-        return -1;
-
-    ff_er_frame_start(s);
-
-    /* decode each macroblock */
-    s->mb_x=0;
-    s->mb_y=0;
-
-    while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
-        if(ff_h261_resync(h)<0)
-            break;
-        h261_decode_gob(h);
-    }
-    MPV_frame_end(s);
-
-    // h261 doesn't have byte aligned codes
-    // store the bits of the next frame that are left in the last byte
-    // in the H261Context and remember the number of stored bits
-    {
-        int bitsleft;
-        int current_pos= get_bits_count(&s->gb)>>3;
-        bitsleft =  (current_pos<<3) - get_bits_count(&s->gb);
-        h->bits_left = - bitsleft;
-        if(bitsleft > 0)
-            h->last_bits= get_bits(&s->gb, 8 - h->bits_left);
-        else
-            h->last_bits = 0;
-    }
-
-assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
-assert(s->current_picture.pict_type == s->pict_type);
-    if(s->low_delay){
-        *pict= *(AVFrame*)&s->current_picture;
-        ff_print_debug_info(s, pict);
-    }else{
-        *pict= *(AVFrame*)&s->last_picture;
-        if(pict)
-            ff_print_debug_info(s, pict);
-    }
-
-    /* Return the Picture timestamp as the frame number */
-    /* we substract 1 because it is added on utils.c    */
-    avctx->frame_number = s->picture_number - 1;
-
-    /* dont output the last pic after seeking */
-    if(s->last_picture_ptr || s->low_delay)
-        *data_size = sizeof(AVFrame);
-#ifdef PRINT_FRAME_TIME
-printf("%Ld\n", rdtsc()-time);
-#endif
-
-return get_consumed_bytes(s, buf_size);
-}
+    static int done = 0;
 
-static int h261_decode_end(AVCodecContext *avctx)
-{
-    H261Context *h= avctx->priv_data;
-    MpegEncContext *s = &h->s;
+    if (done)
+        return;
 
-    MPV_common_end(s);
-    return 0;
+    ff_rl_init(&ff_h261_rl_tcoeff, ff_h261_rl_table_store);
+    done = 1;
 }
-
-AVCodec h261_decoder = {
-    "h261",
-    CODEC_TYPE_VIDEO,
-    CODEC_ID_H261,
-    sizeof(H261Context),
-    h261_decode_init,
-    NULL,
-    h261_decode_end,
-    h261_decode_frame,
-    CODEC_CAP_TRUNCATED,
-};
-
-AVCodecParser h261_parser = {
-    { CODEC_ID_H261 },
-    sizeof(ParseContext),
-    NULL,
-    h261_parse,
-    ff_parse_close,
-};