--- branches/dev-api-4/xvidcore/src/plugins/plugin_2pass2.c 2004/05/06 10:59:19 1447 +++ branches/dev-api-4/xvidcore/src/plugins/plugin_2pass2.c 2004/05/09 14:00:35 1448 @@ -25,7 +25,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * - * $Id: plugin_2pass2.c,v 1.1.2.37 2004-01-31 14:51:56 syskin Exp $ + * $Id: plugin_2pass2.c,v 1.1.2.38 2004-05-09 14:00:35 chl Exp $ * *****************************************************************************/ @@ -177,7 +177,7 @@ twopass_stat_t * stats; /*---------------------------------- - * Histerysis helpers + * Hysteresis helpers *--------------------------------*/ /* This field holds the int2float conversion errors of each quant per @@ -270,6 +270,11 @@ static void first_pass_stats_prepare_data(rc_2pass2_t * rc); static void first_pass_scale_curve_internal(rc_2pass2_t *rc); static void scaled_curve_apply_advanced_parameters(rc_2pass2_t * rc); +#ifdef VBV +static int check_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps); +static int scale_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps); +#endif + #if 0 static void stats_print(rc_2pass2_t * rc); #endif @@ -426,6 +431,41 @@ * shape the curve in the BEFORE/AFTER pair of functions */ scaled_curve_apply_advanced_parameters(rc); + +#ifdef VBV +/* Check curve for VBV compliancy and rescale if necessary */ + + +#ifdef VBV_FORCE + if (rc->param.vbvsize==0) + { + rc->param.vbvsize = 3145728; + rc->param.vbvinitial = 2359296; + rc->param.vbv_maxrate = 4000000; + rc->param.vbv_peakrate = 10000000; + } +#endif + + if (rc->param.vbvsize>0) /* vbvsize==0 switches VBV check off */ + { + const double fps = (double)create->fbase/(double)create->fincr; + int status = check_curve_for_vbv_compliancy(rc, fps); +#ifdef VBV_DEBUG + if (status) + fprintf(stderr,"underflow detected\n Scaling Curve for compliancy... "); +#endif + + status = scale_curve_for_vbv_compliancy(rc, fps); + +#ifdef VBV_DEBUG + if (status==0) + fprintf(stderr,"done.\n"); + else + fprintf(stderr,"impossible.\n"); +#endif + } +#endif + *handle = rc; return(0); } @@ -1380,6 +1420,307 @@ return; } + +#ifdef VBV + +/***************************************************************************** + * VBV compliancy check and scale + * MPEG-4 standard specifies certain restrictions for bitrate/framesize in VBR + * to enable playback on devices with limited readspeed and memory (and which + * aren't...) + * + * DivX profiles have 2 criteria: VBV as in MPEG standard + * a limit on peak bitrate for any 3 seconds + * + * But if VBV is fulfilled, peakrate is automatically fulfilled in any profile + * define so far, so we check for it (for completeness) but correct only VBV + * + *****************************************************************************/ + +#define VBV_COMPLIANT 0 +#define VBV_UNDERFLOW 1 /* video buffer runs empty */ +#define VBV_OVERFLOW 2 /* doesn't exist for VBR encoding */ +#define VBV_PEAKRATE 4 /* peak bitrate (within 3s) violated */ + +static int check_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps) +{ +/* We do all calculations in float, for higher accuracy, and bytes for convenience + + typical values from DivX Home Theater profile: + vbvsize= 384*1024 (384kB), vbvinitial= 288*1024 (75% fill) + maxrate= 4000000 (4MBps), peakrate= 10000000 (10MBps) + + PAL: offset3s = 75 (3 seconds of 25fps) + NTSC: offset3s = 90 (3 seconds of 29.97fps) or 72 (3 seconds of 23.976fps) +*/ + + const float vbvsize = (float)rc->param.vbvsize/8.f; + float vbvfill = (float)rc->param.vbvinitial/8.f; + + const float maxrate = (float)rc->param.vbv_maxrate; + const float peakrate = (float)rc->param.vbv_peakrate; + const float r0 = (int)(maxrate/fps+0.5)/8.f; + + int bytes3s = 0; + int offset3s = (int)(3.f*fps+0.5); + + int i; + for (i=0; inum_frames; i++) { +/* DivX 3s peak bitrate check */ + + bytes3s += rc->stats[i].scaled_length; + if (i>=offset3s) + bytes3s -= rc->stats[i-offset3s].scaled_length; + + if (8.f*bytes3s > 3*peakrate) + return VBV_PEAKRATE; + +/* update vbv fill level */ + + vbvfill += r0 - rc->stats[i].scaled_length; + +/* this check is _NOT_ an "overflow"! only reading from disk stops then */ + if (vbvfill > vbvsize) + vbvfill = vbvsize; + +/* but THIS would be an underflow. report it! */ + if (vbvfill < 0) + return VBV_UNDERFLOW; + } + + return VBV_COMPLIANT; +} +/* idea: min(vbvfill) could be stored to print "minimum buffer fill" */ + + + +static int scale_curve_for_vbv_compliancy(rc_2pass2_t * rc, const float fps) +{ +/* correct any VBV violations. Peak bitrate violations disappears + by this automatically + + This implementation follows + + Westerink, Rajagopalan, Gonzales "Two-pass MPEG-2 variable-bitrate encoding" + IBM J. RES. DEVELOP. VOL 43, No. 4, July 1999, p.471--488 + + Thanks, guys! This paper rocks!!! +*/ + +/* + For each scene of len N, we have to check up to N^2 possible buffer fills. + This works well with MPEG-2 where N==12 or so, but for MPEG-4 it's a + little slow... +*/ + const float vbvsize = (float)rc->param.vbvsize/8.f; + const float vbvinitial = (float)rc->param.vbvinitial/8.f; + + const float maxrate = 0.9*rc->param.vbv_maxrate; + const float vbvlow = 0.10f*vbvsize; + const float r0 = (int)(maxrate/fps+0.5)/8.f; + + int i,k,l,n,violation = 0; + float *scenefactor; + int *scenestart; + int *scenelength; + +/* first step: determine how many "scenes" there are and store their boundaries + we could get all this from existing keyframe_positions, somehow, but there we + don't have a min_scenelength, and it's no big deal to get it again. */ + + const int min_scenelength = 50; + int num_scenes = 0; + int last_scene = -999; + for (i=0; inum_frames; i++) { + if ( (rc->stats[i].type == XVID_TYPE_IVOP) && (i-last_scene>min_scenelength) ) + { + last_scene = i; + num_scenes++; + } + } + + scenefactor = (float*)malloc( num_scenes*sizeof(float) ); + scenestart = (int*)malloc( num_scenes*sizeof(int) ); + scenelength = (int*)malloc( num_scenes*sizeof(int) ); + + if ((!scenefactor) || (!scenestart) || (!scenelength) ) + { + free(scenefactor); + free(scenestart); + free(scenelength); + /* remember: free(0) is valid and does exactly nothing. */ + return -1; + } + +/* count again and safe the length/position */ + + num_scenes = 0; + last_scene = -999; + for (i=0; inum_frames; i++) { + if ( (rc->stats[i].type == XVID_TYPE_IVOP) && (i-last_scene>min_scenelength) ) + { + if (num_scenes>0) + scenelength[num_scenes-1]=i-last_scene; + scenestart[num_scenes]=i; + num_scenes++; + last_scene = i; + } + } + scenelength[num_scenes-1]=i-last_scene; + +/* second step: check for each scene, how much we can scale its frames up or down + such that the VBV restriction is just fulfilled +*/ + + +#define R(k,n) (((n)+1-(k))*r0) /* how much enters the buffer between frame k and n */ + for (l=0; lstats[start]; + + float S0n,Skn; + float f,minf = 99999.f; + + S0n=0.; + for (n=0;n<=length-1;n++) + { + S0n += frames[n].scaled_length; + + k=0; + Skn = S0n; + f = (R(k,n-1) + (vbvinitial - vbvlow)) / Skn; + if (f < minf) + minf = f; + + for (k=1;k<=n;k++) + { + Skn -= frames[k].scaled_length; + + f = (R(k,n-1) + (vbvsize - vbvlow)) / Skn; + if (f < minf) + minf = f; + } + } + + /* special case: at the end, fill buffer up to vbvinitial again + TODO: Allow other values for buffer fill between scenes + e.g. if n=N is smallest f-value, then check for better value */ + + n=length; + k=0; + Skn = S0n; + f = R(k,n-1)/Skn; + if (f < minf) + minf = f; + + for (k=1;k<=n-1;k++) + { + Skn -= frames[k].scaled_length; + + f = (R(k,n-1) + (vbvinitial - vbvlow)) / Skn; + if (f < minf) + minf = f; + } + +#ifdef VBV_DEBUG + printf("Scene %d (Frames %d-%d): VBVfactor %f\n", l, start, start+length-1 , minf); +#endif + + scenefactor[l] = minf; + } +#undef R + +/* last step: now we know of any scene how much it can be scaled up or down without + violating VBV. Next, distribute bits from the evil scenes to the good ones */ + + do + { + float S_red = 0.f; /* how much to redistribute */ + float S_elig = 0.f; /* sum of bit for those scenes you can still swallow something*/ + int l; + + for (l=0;lstats[start]; + + if (scenefactor[l] == 1.) /* exactly 1 means "don't touch this anymore!" */ + continue; + + if (scenefactor[l] > 1.) /* within limits */ + { + for (n= 0; n < length; n++) + S_elig += frames[n].scaled_length; + } + else /* underflowing segment */ + { + for (n= 0; n < length; n++) + { + float newbytes = (float)frames[n].scaled_length * scenefactor[l]; + S_red += (float)frames[n].scaled_length - (float)newbytes; + frames[n].scaled_length =(int)newbytes; + } + scenefactor[l] = 1.f; + } + } + + if (S_red < 1.f) /* no more underflows */ + break; + + if (S_elig < 1.f) + { +#ifdef VBV_DEBUG + fprintf(stderr,"Everything underflowing. \n"); +#endif + free(scenefactor); + free(scenestart); + free(scenelength); + return -2; + } + + const float f_red = (1.f + S_red/S_elig); + +#ifdef VBV_DEBUG + printf("Moving %.0f kB to avoid buffer underflow, correction factor: %.5f\n",S_red/1024.f,f_red); +#endif + + violation=0; + for (l=0; lstats[start]; + + if (scenefactor[l] == 1.) + continue; + + /* there shouldn't be any segments with factor<1 left, so all the rest is >1 */ + + for (n= 0; n < length; n++) + { + frames[n].scaled_length = (int)(frames[n].scaled_length * f_red + 0.5); + } + + scenefactor[l] /= f_red; + if (scenefactor[l] < 1.f) + violation=1; + } + + } while (violation); + + free(scenefactor); + free(scenestart); + free(scenelength); + return 0; +} + + +#endif + + /***************************************************************************** * Still more low level stuff (nothing to do with stats treatment) ****************************************************************************/