[vlc-devel] [PATCH 1/2] Anti-flicker filter initial version
dharani prabhu
dharani.prabhu.s at gmail.com
Sun May 8 21:07:17 CEST 2011
Attached the changes ...
-Dharani
On Sun, May 8, 2011 at 5:48 PM, Laurent Aimar <fenrir at elivagar.org> wrote:
> Hi,
>
> > +struct filter_sys_t
> > +{
> > + int ia_luminance_data[MAX_WINDOW_SZ];
> > + vlc_mutex_t lock;
> > + uint8_t i_window_size;
> > + uint8_t i_softening;
> Using int (or unsigned maybe) would be more natural (same in Filter()
> function).
> > + uint8_t* p_old_data;
> > +};
> > +
>
> >
> +/*****************************************************************************
> > + * Create: allocates Distort video thread output method
> > +
> *****************************************************************************
> > + * This function allocates and initializes a Distort vout method.
> > +
> *****************************************************************************/
> > +static int Create( vlc_object_t *p_this )
> > +{
> > + filter_t *p_filter = (filter_t *)p_this;
> > +
> > + /* Allocate structure */
> > + p_filter->p_sys = malloc( sizeof( *(p_filter->p_sys) ) );
> > + if( p_filter->p_sys == NULL )
> > + return VLC_ENOMEM;
> > +
> > + p_filter->pf_video_filter = Filter;
> > +
> > + /* Initialize the arguments */
> > + p_filter->p_sys->i_window_size = var_CreateGetIntegerCommand(
> p_filter,
> > + FILTER_PREFIX
> "window-size" );
> > + p_filter->p_sys->i_softening = var_CreateGetIntegerCommand(
> p_filter,
> > + FILTER_PREFIX
> "softening-size" );
> > +
> > + p_filter->p_sys->p_old_data = calloc( p_filter->fmt_in.video.i_width
> *
> > +
> (p_filter->fmt_in.video.i_height+1),sizeof(*p_filter->p_sys->p_old_data) );
> > +
> > + memset( p_filter->p_sys->ia_luminance_data, 0,
> > + sizeof(p_filter->p_sys->ia_luminance_data) );
> > + p_filter->p_sys->ia_luminance_data[p_filter->p_sys->i_window_size -
> 1] = 256;
> > +
> > + vlc_mutex_init( &p_filter->p_sys->lock );
> > + var_AddCallback(p_filter,FILTER_PREFIX "window-size",
> > + AntiFlickerCallback, p_filter->p_sys);
> > + var_AddCallback(p_filter,FILTER_PREFIX "softening-size",
> > + AntiFlickerCallback, p_filter->p_sys);
> > +
> > + return VLC_SUCCESS;
> > +}
> I didn't saw it the first time, but you need to check the video type and
> only
> accept the ones you support (probably only planar YUV).
>
> >
> +/*****************************************************************************
> > + * GetLuminanceAvg : The funtion returns the luminance average for a
> picture
> > +
> *****************************************************************************/
> > +static int GetLuminanceAvg( picture_t * p_pic,uint x_offset,uint
> y_offset )
> > +{
> > + uint8_t *p_yplane_out = p_pic->p[Y_PLANE].p_pixels;
> > +
> > + int i_num_lines = p_pic->p[Y_PLANE].i_visible_lines;
> > + int i_num_cols = p_pic->p[Y_PLANE].i_visible_pitch;
> > + int i_in_pitch = p_pic->p[Y_PLANE].i_pitch;
> > +
> > + if( i_num_lines == 0 || i_num_cols == 0 )
> > + return 0;
> > +
> > + uint32_t lum_sum = 0;
> Using 'unsigned' would be more natural here.
> > + for( int i_line = y_offset ; i_line < i_num_lines ; ++i_line )
> > + {
> > + for( int i_col = x_offset ; i_col < i_num_cols; ++i_col )
> > + {
> > + lum_sum += p_yplane_out[i_line*i_in_pitch+i_col];
> > + }
> > + }
> > + return lum_sum / ( i_num_lines * i_num_cols );
> It might improve the quality to round to the nearest integer the returned
> value, no?
> > +}
> I am sorry, but I mix up between fields of video_format_t and fields of
> plane_t.
> Could you just revert that change (ie x/y_offset are always 0 here).
>
> >
> +/*****************************************************************************
> > + * Filter: adjust the luminance value and renders
> > +
> *****************************************************************************
> > + * The function uses moving average of past frames to adjust the
> luminance
> > + * of current frame also applies temporaral smoothening if enabled.
> > +
> *****************************************************************************/
> > +static picture_t *Filter( filter_t *p_filter, picture_t *p_pic )
> > +{
> > + if( !p_pic ) return NULL;
> > +
> > + picture_t *p_outpic = filter_NewPicture( p_filter );
> > + if( !p_outpic )
> > + {
> > + picture_Release( p_pic );
> > + return NULL;
> > + }
> > +
> > + /****************** Get variables *************************/
> > +
> > + uint8_t i_window_size;
> > + uint8_t i_softening;
> unsigned or int.
> > +
> > + vlc_mutex_lock( &p_filter->p_sys->lock );
> > + i_window_size = p_filter->p_sys->i_window_size;
> > + i_softening = p_filter->p_sys->i_softening;
> > + vlc_mutex_unlock( &p_filter->p_sys->lock );
> > +
> > + uint8_t *p_yplane_in = p_pic->p[Y_PLANE].p_pixels;
> > + uint8_t *p_yplane_out = p_outpic->p[Y_PLANE].p_pixels;
> > + bool scene_changed = false;
> > +
> > + int16_t i_num_lines = p_pic->p[Y_PLANE].i_visible_lines;
> > + int16_t i_num_cols = p_pic->p[Y_PLANE].i_visible_pitch;
> unsigned or int.
>
> > + int16_t i_in_pitch = p_pic->p[Y_PLANE].i_pitch;
> > + int16_t i_out_pitch = p_outpic->p[Y_PLANE].i_pitch;
> int for pitches.
> > +
> > + /******** Get the luminance average for the current picture
> ********/
> > + int lum_avg =
> GetLuminanceAvg(p_pic,p_filter->fmt_in.video.i_x_offset,
> > + p_filter->fmt_in.video.i_y_offset );
> > + lum_avg = lum_avg > 255 ? 255 : lum_avg;
> I think there's no need to check against 255, by design it will be
> bound to 0-255.
> > +
> > + /*Identify as scene change if the luminance average deviates
> > + more than the threshold value or if it is the first frame*/
> > +
> > + if( abs(lum_avg - p_filter->p_sys->
> > + ia_luminance_data[i_window_size - 1]) > SCENE_CHANGE_THRESHOLD
> > + || p_filter->p_sys->ia_luminance_data[i_window_size - 1] == 256)
> > + {
> > + scene_changed = true;
> > + }
> > +
> > + /******* Compute the adjustment factor using moving average
> ********/
> > + float scale = 1.0;
> > +
> > + if ( scene_changed )
> > + {
> > + //reset the luminance data
> > + for (int i = 0; i < i_window_size; ++i)
> > + p_filter->p_sys->ia_luminance_data[i] = lum_avg;
> > + }
> > + else
> > + {
> > + for (int i = 0; i < i_window_size-1 ; ++i)
> > + p_filter->p_sys->ia_luminance_data[i] =
> > + p_filter->p_sys->ia_luminance_data[i+1];
> > +
> > + p_filter->p_sys->ia_luminance_data[i_window_size - 1] = lum_avg;
> > +
> > + if (lum_avg > 0)
> > + {
> > + scale = 1.0f/lum_avg;
> > + double filt = 0;
> > + for (int i = 0; i < i_window_size; i++)
> > + filt += (float) p_filter->p_sys->ia_luminance_data[i];
> > + scale *= (filt/i_window_size);
> You could merged the 2 scale modifications (easier to understand).
> > + }
> > + }
> > +
> > +
> > + if( scene_changed )
> > + plane_CopyPixels( &p_outpic->p[Y_PLANE], &p_pic->p[Y_PLANE] );
> > + else
> > + {
> > + /******* Apply the adjustment factor to each pixel on Y_PLANE
> ********/
> > + uint8_t shift = 8;
> > + int scale_num = __MIN(scale,255) * ( 1 << shift );
> > +
> > + for( int16_t i_line = 0 ; i_line < i_num_lines ; i_line++ )
> > + {
> > + for( int16_t i_col = 0; i_col < i_num_cols ; i_col++ )
> unsigned or int (same as i_num_lines/i_num_cols).
> > + {
> > + uint8_t pixel_data =
> p_yplane_in[i_line*i_in_pitch+i_col];
> > + int pixel_val = ( scale_num * pixel_data +
> > + (1<<(shift -1)) ) >> shift;
> > + p_yplane_out[i_line*i_out_pitch+i_col] =
> > + (pixel_val>255) ? 255:pixel_val;
> > + }
> > + }
> > + }
> You could merged the 2 "if/else" blocks.
>
> > +
> > + /***************** Copy the UV plane as such
> *****************************/
> > + plane_CopyPixels( &p_outpic->p[U_PLANE], &p_pic->p[U_PLANE] );
> > + plane_CopyPixels( &p_outpic->p[V_PLANE], &p_pic->p[V_PLANE] );
> > +
> > + if (scene_changed || i_softening == 0)
> > + {
> > + return CopyInfoAndRelease( p_outpic, p_pic );
> > + }
> > +
> > + /******* Temporal softening phase. Adapted from code by Steven Don
> ******/
> > + uint8_t *src1, *src2;
> > + long diff, ofs, sum;
> int, you could alo move diff and sum inside the loop
> > +
> > + ofs = (i_num_lines * i_out_pitch + i_num_cols);
> > + src1 = p_outpic->p[Y_PLANE].p_pixels;
> > + src2 = p_filter->p_sys->p_old_data;
> > +
> > + do
> > + {
> > + diff = abs(*src1 - *src2);
> > + if (diff < i_softening)
> > + {
> > + if (diff > (i_softening >> 1))
> > + {
> > + sum = *src1 + *src1 + *src2;
> > + *src2 = sum / 3;
> > + }
> > + }
> > + else
> > + {
> > + *src2 = *src1;
> > + }
> > + *src1 = *src2;
> > + src1++; src2++;
> > + } while (--ofs);
> That does not work, you need to iterate over lines/cols to correctly take
> care
> that p_outpic->p[Y_PLANE].p_pixels uses p_outpic->p[Y_PLANE].i_pitch and
> p_filter->p_sys->p_old_data uses p_filter->fmt_out.i_width as pitch.
>
> > +
> > + return CopyInfoAndRelease( p_outpic, p_pic );
> > +}
>
> Sorry for the few points I missed the first time.
>
> Regards,
>
> --
> fenrir
>
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