View source for DGDecode/MPEG2Source

{{FilterCat|External_filters|Plugin_functions|Source_filters}}

'''Back to [[DGDecode]] &larr;'''
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== Description ==
Frame accurate MPEG1/2 decoder. Official documentation: http://rationalqm.us/dgmpgdec/DGDecodeManual.html <br>
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== [[Script variables|Syntax and Parameters]] ==
:{{Template:FuncDef|MPEG2Source (''string d2v'', ''int'' "idct", ''int'' "cpu", ''bool'' "iPP", ''int'' "moderate_h", ''int'' "moderate_v", ''string'' "cpu2", ''int'' "upConv", ''bool'' "iCC", ''bool'' "i420", ''int'' "info", ''bool'' "showQ", ''bool'' "fastMC")}}
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::{{Par2|d2v|string| " "}}
:::DGIndex Project File [Required]
:::'''Note:''' PATH can be ignored if "project.d2v" is in the same directory as your AviSynth (*.avs) script.
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::{{Par2|idct|int|0}}
:::iDCT Algorithm.
:::For more infomation on iDCTs please see iDCT Algorithm Notes. Please see SIMD Instructions for supported CPUs.
::::*0 : Use value specified by DGIndex
::::*1 : 32-bit [[MMX]]
::::*2 : 32-bit [[SSE]][[MMX]]
::::*3 : 32-bit [[SSE2]][[MMX]]
::::*4 : 64-bit Floating Point
::::*5 : 64-bit IEEE-1180 Reference
::::*6 : 32-bit SSEMMX (Skal)
::::*7 : 32-bit Simple MMX (XviD)
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::{{Par2|cpu|int|0}}
:::Post-Processing Quickset Options.
:::(Y=luma, C=chroma, H=horizontal, V=vertical)
::::*0 : DISABLE POST-PROCESSING
::::*1 : DEBLOCK_Y_H
::::*2 : DEBLOCK_Y_H, DEBLOCK_Y_V
::::*3 : DEBLOCK_Y_H, DEBLOCK_Y_V, DEBLOCK_C_H
::::*4 : DEBLOCK_Y_H, DEBLOCK_Y_V, DEBLOCK_C_H, DEBLOCK_C_V
::::*5 : DEBLOCK_Y_H, DEBLOCK_Y_V, DEBLOCK_C_H, DEBLOCK_C_V, DERING_Y
::::*6 : DEBLOCK_Y_H, DEBLOCK_Y_V, DEBLOCK_C_H, DEBLOCK_C_V, DERING_Y, DERING_C
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::{{Par2|iPP|bool|auto}}
:::Post-Processing Mode.
:::DGDecode automatically uses the PROGRESSIVE_FRAME flag to switch between field/frame based post-processing on a per-frame-basis.
:::You should only specify the iPP parameter if you want to force DGDecode to use a particular post-processing mode.
::::*[unspecified] : follow the PROGRESSIVE_FRAME flag
::::*true : force field-based (interlaced) post-processing
::::*false : force frame-based (progressive) post-processing
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::{{Par2|moderate_h|int|20}}
::{{Par2|moderate_v|int|40}}
:::Horizontal and Vertical Block Detection Sensitivity. Smaller values are stronger, use with care.
:::Range: 0 to 255
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::{{Par2|cpu2|string| " "}}
:::Post-Processing Custom Options.
:::Specify a six character string of x's and o's according to list below. (case-insensitive)
:::Each "x" enables the corresponding post-processing feature.
:::Each "o" disables the corresponding post-processing feature.
::::*character 1 : luma horizontal deblocking
::::*character 2 : luma vertical deblocking
::::*character 3 : chroma horizontal deblocking
::::*character 4 : chroma vertical deblocking
::::*character 5 : luma deringing
::::*character 6 : chroma deringing
:::For example, to enable chroma-only post-processing use:
:::<pre>MPEG2Source("project.d2v", cpu2="ooxxox")</pre>
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::{{Par2|upConv|int|0}}
:::Upsample from 4:2:0 to YUY2 (4:2:2) or RGB24.
::::*0 : Do not upsample
::::*1 : Upsample to [[YUY2]] (ignored if input is already 4:2:2)
::::*2 : Upsample to [[RGB24]]
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::{{Par2|iCC|bool|auto}}
:::Upsampling Mode.
:::DGDecode automatically uses the PROGRESSIVE_FRAME flag to switch between field/frame based upsampling on a per-frame-basis.
:::You should '''''only''''' specify the iCC parameter if you want to force DGDecode to use a particular upsampling mode.
::::*[unspecified] : follow the PROGRESSIVE_FRAME flag
::::*true : force field-based (interlaced) upsampling
::::*false : force frame-based (progressive) upsampling
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::{{Par2|i420|bool|false}}
:::Output I420 Colorspace. Possibly required by some legacy applications.
:::Ignored if the input is not YV12 (4:2:0), or if upsampling with '''upConv'''=1 or 2.
::::*true : output [[I420]]
::::*false : output [[YV12]]
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::{{Par2|info|int|0}}
:::Debug Information
::::*0 : Do not generate debug information
::::*1 : Overlay debug information on the video
::::*2 : Output debug information via OutputDebugString()
::::*3 : Output hints in the video (as defined in utilities.cpp/utilities.h)
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::{{Par2|showQ|bool|false}}
:::Show Macroblock Quantizers.
::::*true : Show quantizers
::::*false : Do not show quantizers
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::{{Par2|fastMC|bool|false}}
:::Vlad's Fast Motion Compensation. Very small speedup, but with degraded accuracy.
:::For testing purposes, and may be removed in a future version. Requires [[SSE]] or 3DNow!, please see iDCT Algorithm Notes for supported CPUs.
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==Examples==
MPEG2Source() should be used only with MPEG-1 and MPEG-2 video sources.<br/>
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*To do plain YV12 decoding:
:<pre>MPEG2Source("project.d2v", cpu=0)</pre>
:Note: PATH can be ignored if "project.d2v" is in the same directory as your AviSynth (*.avs) script.
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*To do deblocking only:
:<pre>MPEG2Source("project.d2v", cpu=4, iPP=true, moderate_v=20)</pre>
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*To do deblocking on an interlaced source with increased vertical sensitivity:
:<pre>MPEG2Source("project.d2v", cpu=4, iPP=true, moderate_v=20)</pre>
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*To do deringing only:
:<pre>MPEG2Source("project.d2v", cpu2="ooooxx")</pre>
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*To select the optimized 32-bit SSE2 iDCT and also output I420 colorspace:
:<pre>MPEG2Source("project.d2v", idct=5, i420=true)</pre>
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*To convert to YUY2 based on the PROGRESSIVE_FRAME flag:
:<pre>MPEG2Source("project.d2v", upConv=1)</pre>
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*To do display onscreen information about the video:
:<pre>MPEG2Source("project.d2v", info=1</pre>
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==iDCT Algorithm Notes==
The FlasKMPEG readme file contains an excellent technical description of iDCTs. It states:
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:''"The video information inside MPEG files is stored in the frequency domain rather than in the spatial domain (the images we see). That way, the information gets compacted and that compaction can be used to compress (reduce) the amount of information you have to send over the transmission channel. MPEG uses the DCT (Discrete Cosine Transform) to translate spatial information into frequency information. To bring back the spatial information from the MPEG stream you have to apply the iDCT, that is, the Inverse Discrete Cosine Transform, that undoes the DCT that was used during encoding."''

:''"Although MPEG is almost deterministic (given a MPEG stream the output should be identical in all decoders), the standard has a degree of freedom when choosing the iDCT to use. That way, the decoder can be more easily implemented depending on the hardware below it. What the standard requires from the decoder is that the iDCT meets IEEE-1180 specs, or in plain words, that the error from the iDCT doesn't go beyond that the ones pointed out in the IEEE-1180."''

Which iDCT you should use depends primarily on what CPU you have and to a lesser degree, on how accurate an iDCT you desire. Most people will not be able to tell the difference in quality between these algorithms but they can be easily observed by combining the AviSynth filters [[Subtract]]() and [[Levels]](). All of the available options are IEEE-1180 compliant, except for '''[[SSE]]/[[MMX]] (Skal)'''.

*Qualitywise: '''IEEE-1180 Reference''' > '''64-bit Floating Point''' > '''Simple MMX (XviD)''' > Remaining iDCTs.
*Speedwise: '''SSE2/MMX''' and '''SSE/MMX (Skal)''' are usually the fastest. The '''IEEE-1180 Reference''' is easily the slowest.
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