Author: gpoirier Date: Sat Nov 18 13:23:05 2006 New Revision: 21012 Modified: trunk/DOCS/man/en/mplayer.1 Log: group together "quality" control options Modified: trunk/DOCS/man/en/mplayer.1 ============================================================================== --- trunk/DOCS/man/en/mplayer.1 (original) +++ trunk/DOCS/man/en/mplayer.1 Sat Nov 18 13:23:05 2006 @@ -8496,6 +8496,100 @@ you need realtime encoding. . .TP +.B (no)qpel +MPEG-4 uses a half pixel precision for its motion search by default. +The standard proposes a mode where encoders are allowed to use quarter +pixel precision. +This option usually results in a sharper image. +Unfortunately it has a great impact on bitrate and sometimes the +higher bitrate use will prevent it from giving a better image +quality at a fixed bitrate. +It is better to test with and without this option and see whether it +is worth activating. +. +.TP +.B (no)gmc +Enable Global Motion Compensation, which makes Xvid generate special +frames (GMC-frames) which are well suited for Pan/\:Zoom/\:Rotating images. +Whether or not the use of this option will save bits is highly +dependent on the source material. +. +.TP +.B (no)trellis +Trellis Quantization is a kind of adaptive quantization method that +saves bits by modifying quantized coefficients to make them more +compressible by the entropy encoder. +Its impact on quality is good, and if VHQ uses too much CPU for you, +this setting can be a good alternative to save a few bits (and gain +quality at fixed bitrate) at a lesser cost than with VHQ (default: on). +. +.TP +.B (no)cartoon +Activate this if your encoded sequence is an anime/\:cartoon. +It modifies some Xvid internal thresholds so Xvid takes better decisions on +frame types and motion vectors for flat looking cartoons. +. +.TP +.B (no)chroma_me +The usual motion estimation algorithm uses only the luminance information to +find the best motion vector. +However for some video material, using the chroma planes can help find +better vectors. +This setting toggles the use of chroma planes for motion estimation +(default: on). +. +.TP +.B (no)chroma_opt +Enable a chroma optimizer prefilter. +It will do some extra magic on color information to minimize the +stepped-stairs effect on edges. +It will improve quality at the cost of encoding speed. +It reduces PSNR by nature, as the mathematical deviation to the original +picture will get bigger, but the subjective image quality will raise. +Since it works with color information, you might want to turn it off when +encoding in grayscale. +. +.TP +.B (no)hq_ac +Activates high-quality prediction of AC coefficients for intra frames from +neighbor blocks (default: on). +. +.TP +.B vhq=<0\-4> +The motion search algorithm is based on a search in the usual color domain +and tries to find a motion vector that minimizes the difference between the +reference frame and the encoded frame. +With this setting activated, Xvid will also use the frequency domain (DCT) +to search for a motion vector that minimizes not only the spatial +difference but also the encoding length of the block. +Fastest to slowest: +.PD 0 +.RSs +.IPs 0 +off +.IPs 1 +mode decision (inter/\:intra MB) (default) +.IPs 2 +limited search +.IPs 3 +medium search +.IPs 4 +wide search +.RE +.PD 1 +. +.TP +.B (no)lumi_mask +Adaptive quantization allows the macroblock quantizers to vary inside +each frame. +This is a 'psychosensory' setting that is supposed to make use of the +fact that the human eye tends to notice fewer details in very bright +and very dark parts of the picture. +It compresses those areas more strongly than medium ones, which will +save bits that can be spent again on other frames, raising overall +subjective quality and possibly reducing PSNR. +. +.TP .B (no)interlacing Encode the fields of interlaced video material. Turn this option on for interlaced content. @@ -8661,100 +8755,6 @@ own risks! . .TP -.B (no)qpel -MPEG-4 uses a half pixel precision for its motion search by default. -The standard proposes a mode where encoders are allowed to use quarter -pixel precision. -This option usually results in a sharper image. -Unfortunately it has a great impact on bitrate and sometimes the -higher bitrate use will prevent it from giving a better image -quality at a fixed bitrate. -It is better to test with and without this option and see whether it -is worth activating. -. -.TP -.B (no)gmc -Enable Global Motion Compensation, which makes Xvid generate special -frames (GMC-frames) which are well suited for Pan/\:Zoom/\:Rotating images. -Whether or not the use of this option will save bits is highly -dependent on the source material. -. -.TP -.B (no)trellis -Trellis Quantization is a kind of adaptive quantization method that -saves bits by modifying quantized coefficients to make them more -compressible by the entropy encoder. -Its impact on quality is good, and if VHQ uses too much CPU for you, -this setting can be a good alternative to save a few bits (and gain -quality at fixed bitrate) at a lesser cost than with VHQ (default: on). -. -.TP -.B (no)cartoon -Activate this if your encoded sequence is an anime/\:cartoon. -It modifies some Xvid internal thresholds so Xvid takes better decisions on -frame types and motion vectors for flat looking cartoons. -. -.TP -.B (no)chroma_me -The usual motion estimation algorithm uses only the luminance information to -find the best motion vector. -However for some video material, using the chroma planes can help find -better vectors. -This setting toggles the use of chroma planes for motion estimation -(default: on). -. -.TP -.B (no)chroma_opt -Enable a chroma optimizer prefilter. -It will do some extra magic on color information to minimize the -stepped-stairs effect on edges. -It will improve quality at the cost of encoding speed. -It reduces PSNR by nature, as the mathematical deviation to the original -picture will get bigger, but the subjective image quality will raise. -Since it works with color information, you might want to turn it off when -encoding in grayscale. -. -.TP -.B (no)hq_ac -Activates high-quality prediction of AC coefficients for intra frames from -neighbor blocks (default: on). -. -.TP -.B vhq=<0\-4> -The motion search algorithm is based on a search in the usual color domain -and tries to find a motion vector that minimizes the difference between the -reference frame and the encoded frame. -With this setting activated, Xvid will also use the frequency domain (DCT) -to search for a motion vector that minimizes not only the spatial -difference but also the encoding length of the block. -Fastest to slowest: -.PD 0 -.RSs -.IPs 0 -off -.IPs 1 -mode decision (inter/\:intra MB) (default) -.IPs 2 -limited search -.IPs 3 -medium search -.IPs 4 -wide search -.RE -.PD 1 -. -.TP -.B (no)lumi_mask -Adaptive quantization allows the macroblock quantizers to vary inside -each frame. -This is a 'psychosensory' setting that is supposed to make use of the -fact that the human eye tends to notice fewer details in very bright -and very dark parts of the picture. -It compresses those areas more strongly than medium ones, which will -save bits that can be spent again on other frames, raising overall -subjective quality and possibly reducing PSNR. -. -.TP .B quant_intra_matrix=<filename> Load a custom intra matrix file. You can build such a file with xvid4conf's matrix editor.