From: David Flynn Date: Sat, 8 Aug 2009 13:12:40 +0000 (+0100) Subject: video_filter/canvas: various aspect-ratio related fixes X-Git-Tag: 1.1.0-ff~4465 X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=c2752f8142a31b728b797ba915b59fc671744181;p=vlc video_filter/canvas: various aspect-ratio related fixes video_filter/canvas: various aspect-ratio related fixes - Remove silly defaulting to 4:3. Instead, compute PAR based upon SAR of input video and canvas size. - Update documentation to remove ambiguity over what is meant by aspect-ratio - Fix subpicture calculations to (a) be much simpler, (b) correctly calculate width and height Signed-off-by: Ilkka Ollakka --- diff --git a/modules/video_filter/canvas.c b/modules/video_filter/canvas.c index ecca56fcbd..a083b18289 100644 --- a/modules/video_filter/canvas.c +++ b/modules/video_filter/canvas.c @@ -43,16 +43,54 @@ static void Destroy( vlc_object_t * ); static picture_t *Filter( filter_t *, picture_t * ); static int alloc_init( filter_t *, void * ); -#define WIDTH_TEXT N_( "Image width" ) +/* This module effectively implements a form of picture-in-picture. + * - The outer picture is called the canvas. + * - The innter picture is callsed the subpicture. + * + * NB, all of the following operatons take into account aspect ratio + * + * A canvas is of canvas_{width,height}. + * In Pad mode: + * - The subpicture is upconverted with a inverse scalefactor of: + * (The size of subpicture's largest dimension) + * -------------------------------------------- + * (The size of canvas's equivalent dimension) + * + * Ie, The subpicture's largest dimension is made equal to the + * equivalent canvas dimension. + * + * - The upconverted subpicture's smallest dimension is then padded + * to make the upconverted subpicture have the same dimensions of + * the canvas. + * + * In Crop mode: + * - The subpicture is upconverted with an inverse scalefactor of: + * (The size of subpicture's smallest dimension) + * -------------------------------------------- + * (The size of canvas's equivalent dimension) + * + * Ie, The subpicture's smallest dimension is made equal to the + * equivalent canvas dimension. (The subpicture will then be + * larger than the canvas) + * + * - The upconverted subpicture's largest dimension is then cropped + * to make the upconverted subpicture have the same dimensions of + * the canvas. + */ + +/* NB, use of `padd' in this module is a 16-17th Century spelling of `pad' */ + +#define WIDTH_TEXT N_( "Output width" ) #define WIDTH_LONGTEXT N_( \ - "Image width" ) -#define HEIGHT_TEXT N_( "Image height" ) + "Output (canvas) image width" ) +#define HEIGHT_TEXT N_( "Output height" ) #define HEIGHT_LONGTEXT N_( \ - "Image height" ) -#define ASPECT_TEXT N_( "Aspect ratio" ) + "Output (canvas) image height" ) +#define ASPECT_TEXT N_( "Output picture aspect ratio" ) #define ASPECT_LONGTEXT N_( \ - "Set aspect (like 4:3) of the video canvas" ) -#define PADD_TEXT N_( "Padd video" ) + "Set the canvas' picture aspect ratio. " \ + "If omitted, the canvas is assumed to have the same SAR as the input." ) +#define PADD_TEXT N_( "Pad video" ) #define PADD_LONGTEXT N_( \ "If enabled, video will be padded to fit in canvas after scaling. " \ "Otherwise, video will be cropped to fix in canvas after scaling." ) @@ -63,7 +101,7 @@ static int alloc_init( filter_t *, void * ); * Module descriptor *****************************************************************************/ vlc_module_begin () - set_description( N_("Automatically resize and padd a video") ) + set_description( N_("Automatically resize and pad a video") ) set_capability( "video filter2", 0 ) set_callbacks( Activate, Destroy ) @@ -75,7 +113,7 @@ vlc_module_begin () add_integer_with_range( CFG_PREFIX "height", 0, 0, INT_MAX, NULL, HEIGHT_TEXT, HEIGHT_LONGTEXT, false ) - add_string( CFG_PREFIX "aspect", "4:3", NULL, + add_string( CFG_PREFIX "aspect", NULL, NULL, ASPECT_TEXT, ASPECT_LONGTEXT, false ) add_bool( CFG_PREFIX "padd", true, NULL, @@ -97,12 +135,13 @@ struct filter_sys_t static int Activate( vlc_object_t *p_this ) { filter_t *p_filter = (filter_t *)p_this; - unsigned int i_width, i_height; - es_format_t fmt; + unsigned i_canvas_width; /* width of output canvas */ + unsigned i_canvas_height; /* height of output canvas */ + unsigned i_canvas_aspect; /* canvas PictureAspectRatio */ + es_format_t fmt; /* target format after up/down conversion */ char psz_croppadd[100]; int i_padd,i_offset; char *psz_aspect, *psz_parser; - int i_aspect; bool b_padd; if( !p_filter->b_allow_fmt_out_change ) @@ -120,39 +159,49 @@ static int Activate( vlc_object_t *p_this ) config_ChainParse( p_filter, CFG_PREFIX, ppsz_filter_options, p_filter->p_cfg ); - i_width = var_CreateGetInteger( p_filter, CFG_PREFIX "width" ); - i_height = var_CreateGetInteger( p_filter, CFG_PREFIX "height" ); + i_canvas_width = var_CreateGetInteger( p_filter, CFG_PREFIX "width" ); + i_canvas_height = var_CreateGetInteger( p_filter, CFG_PREFIX "height" ); - if( i_width == 0 || i_height == 0 ) + if( i_canvas_width == 0 || i_canvas_height == 0 ) { msg_Err( p_filter, "Width and height options must be set" ); return VLC_EGENERIC; } - if( i_width & 1 || i_height & 1 ) + if( i_canvas_width & 1 || i_canvas_height & 1 ) { + /* If this restriction were ever relaxed, it is very important to + * get the field polatiry correct */ msg_Err( p_filter, "Width and height options must be even integers" ); return VLC_EGENERIC; } psz_aspect = var_CreateGetNonEmptyString( p_filter, CFG_PREFIX "aspect" ); - if( !psz_aspect ) + if( psz_aspect ) { - msg_Err( p_filter, "Aspect ratio must be set" ); - return VLC_EGENERIC; + psz_parser = strchr( psz_aspect, ':' ); + int numerator = atoi( psz_aspect ); + int denominator = psz_parser ? atoi( psz_parser+1 ) : 0; + denominator = denominator == 0 ? 1 : denominator; + i_canvas_aspect = numerator * VOUT_ASPECT_FACTOR / denominator; + free( psz_aspect ); + + if( numerator <= 0 || denominator < 0 ) + { + msg_Err( p_filter, "Aspect ratio must be strictly positive" ); + return VLC_EGENERIC; + } } - psz_parser = strchr( psz_aspect, ':' ); - if( psz_parser ) psz_parser++; - if( psz_parser && atoi( psz_parser ) > 0 ) - i_aspect = atoi( psz_aspect ) * VOUT_ASPECT_FACTOR / atoi( psz_parser ); else - i_aspect = atof( psz_aspect ) * VOUT_ASPECT_FACTOR; - free( psz_aspect ); - - if( i_aspect <= 0 ) { - msg_Err( p_filter, "Aspect ratio must be strictly positive" ); - return VLC_EGENERIC; + /* if there is no user supplied aspect ratio, assume the canvas + * has the same sample aspect ratio as the subpicture */ + /* aspect = subpic_sar * canvas_width / canvas_height + * where subpic_sar = subpic_ph * subpic_par / subpic_pw */ + i_canvas_aspect = (uint64_t) p_filter->fmt_in.video.i_height + * p_filter->fmt_in.video.i_aspect + * i_canvas_width + / (i_canvas_height * p_filter->fmt_in.video.i_width); } b_padd = var_CreateGetBool( p_filter, CFG_PREFIX "padd" ); @@ -173,36 +222,42 @@ static int Activate( vlc_object_t *p_this ) es_format_Copy( &fmt, &p_filter->fmt_in ); - fmt.video.i_width = i_width; - fmt.video.i_height = ( p_filter->fmt_in.video.i_height * i_width ) - / p_filter->fmt_in.video.i_width; - fmt.video.i_height = ( fmt.video.i_height * i_aspect ) - / p_filter->fmt_in.video.i_aspect; + /* one dimension will end up with one of the following: */ + fmt.video.i_width = i_canvas_width; + fmt.video.i_height = i_canvas_height; if( b_padd ) { /* Padd */ - if( fmt.video.i_height > i_height ) + if( i_canvas_aspect > p_filter->fmt_in.video.i_aspect ) { - fmt.video.i_height = i_height; - fmt.video.i_width = ( p_filter->fmt_in.video.i_width * i_height ) - / p_filter->fmt_in.video.i_height; - fmt.video.i_width = ( fmt.video.i_width * p_filter->fmt_in.video.i_aspect ) - / i_aspect; + /* The canvas has a wider aspect than the subpicture: + * ie, pillarbox the [scaled] subpicture */ + /* The following is derived form: + * width = upconverted_subpic_height * subpic_par / canvas_sar + * where canvas_sar = canvas_width / (canvas_height * canvas_par) + * then simplify */ + fmt.video.i_width = i_canvas_width + * p_filter->fmt_in.video.i_aspect + / i_canvas_aspect; if( fmt.video.i_width & 1 ) fmt.video.i_width -= 1; - i_padd = (i_width - fmt.video.i_width) / 2; + i_padd = (i_canvas_width - fmt.video.i_width) / 2; i_offset = (i_padd & 1); - /* Gruik */ snprintf( psz_croppadd, 100, "croppadd{paddleft=%d,paddright=%d}", i_padd - i_offset, i_padd + i_offset ); } else { + /* The canvas has a taller aspect than the subpicture: + * ie, letterbox the [scaled] subpicture */ + fmt.video.i_height = i_canvas_height + * i_canvas_aspect + / p_filter->fmt_in.video.i_aspect; if( fmt.video.i_height & 1 ) fmt.video.i_height -= 1; - i_padd = (i_height - fmt.video.i_height ) / 2; + + i_padd = (i_canvas_height - fmt.video.i_height ) / 2; i_offset = (i_padd & 1); - /* Gruik */ snprintf( psz_croppadd, 100, "croppadd{paddtop=%d,paddbottom=%d}", i_padd - i_offset, i_padd + i_offset ); } @@ -210,32 +265,40 @@ static int Activate( vlc_object_t *p_this ) else { /* Crop */ - if( fmt.video.i_height < i_height ) + if( i_canvas_aspect < p_filter->fmt_in.video.i_aspect ) { - fmt.video.i_height = i_height; - fmt.video.i_width = ( p_filter->fmt_in.video.i_width * i_height ) - / p_filter->fmt_in.video.i_height; - fmt.video.i_width = ( fmt.video.i_width * p_filter->fmt_in.video.i_aspect ) - / i_aspect; + /* The canvas has a narrower aspect than the subpicture: + * ie, crop the [scaled] subpicture horizontally */ + fmt.video.i_width = i_canvas_width + * p_filter->fmt_in.video.i_aspect + / i_canvas_aspect; if( fmt.video.i_width & 1 ) fmt.video.i_width -= 1; - i_padd = (fmt.video.i_width - i_width) / 2; - i_offset = (i_padd & 1); - /* Gruik */ + i_padd = (fmt.video.i_width - i_canvas_width) / 2; + i_offset = (i_padd & 1); snprintf( psz_croppadd, 100, "croppadd{cropleft=%d,cropright=%d}", i_padd - i_offset, i_padd + i_offset ); } else { + /* The canvas has a shorter aspect than the subpicture: + * ie, crop the [scaled] subpicture vertically */ + fmt.video.i_height = i_canvas_height + * i_canvas_aspect + / p_filter->fmt_in.video.i_aspect; if( fmt.video.i_height & 1 ) fmt.video.i_height -= 1; - i_padd = (fmt.video.i_height - i_height) / 2; + + i_padd = (fmt.video.i_height - i_canvas_height) / 2; i_offset = (i_padd & 1); - /* Gruik */ snprintf( psz_croppadd, 100, "croppadd{croptop=%d,cropbottom=%d}", i_padd - i_offset, i_padd + i_offset ); } } + /* xxx, should the clean area include the letter-boxing? + * probably not, as some codecs can make use of that information + * and it should be a scaled version of the input clean area + * -- davidf */ fmt.video.i_visible_width = fmt.video.i_width; fmt.video.i_visible_height = fmt.video.i_height; @@ -248,16 +311,16 @@ static int Activate( vlc_object_t *p_this ) fmt = *filter_chain_GetFmtOut( p_sys->p_chain ); es_format_Copy( &p_filter->fmt_out, &fmt ); - p_filter->fmt_out.video.i_aspect = i_aspect * i_width / i_height; + p_filter->fmt_out.video.i_aspect = i_canvas_aspect; - if( p_filter->fmt_out.video.i_width != i_width - || p_filter->fmt_out.video.i_height != i_height ) + if( p_filter->fmt_out.video.i_width != i_canvas_width + || p_filter->fmt_out.video.i_height != i_canvas_height ) { msg_Warn( p_filter, "Looks like something went wrong. " "Output size is %dx%d while we asked for %dx%d", p_filter->fmt_out.video.i_width, p_filter->fmt_out.video.i_height, - i_width, i_height ); + i_canvas_width, i_canvas_height ); } p_filter->pf_video_filter = Filter;