if this option is checked, the Set Format dialog always recalculates the Aspect ratio setting based upon the given Canvas size. This ensures pixels are always square.
\item[Color model:]
- the project will be stored in the color model video that is selected in the dropdown.
+ the internal color space of Cinelerra GG is X11 sRGB without color profile. Cinelerra always switches to sRGB when applying filters or using the compositing engine. Different case for decoding/playback or encoding/output; the project will be stored in the color model video that is selected in the dropdown.
Color model is important for video playback because video has the disadvantage of being slow compared to audio.
Video is stored on disk in one colormodel, usually a YUV derivative.
When played back, Cinelerra decompresses it from the file format directly into the format of the output device.
\begin{description}
\item[RGB-8 bit]
- Allocates 8 bits for the R, G, and B channels and no alpha. This is normally used for uncompressed media with low dynamic range.
+ Allocates 8\,bits for the R, G, and B channels and no alpha. This is normally used for uncompressed media with low dynamic range.
\item[RGBA-8 bit]
- Allocates an alpha channel to the 8 bit RGB colormodel. It can be used for overlaying multiple tracks.\\
+ Allocates an alpha channel to the 8\,bit RGB colormodel. It can be used for overlaying multiple tracks.\\
\item[RGB-Float]
- Allocates a 32 bit float for the R, G, and B channels and no alpha. This is used for high dynamic range processing with no transparency.
+ Allocates a 32\,bit float for the R, G, and B channels and no alpha. This is used for high dynamic range processing with no transparency.
\item[RGBA-Float]
- This adds a 32 bit float for alpha to RGB-Float. It is used for high dynamic range processing with transparency.\\
+ This adds a 32\,bit float for alpha to RGB-Float. It is used for high dynamic range processing with transparency. Or when we don't want to lose data during workflow, for example in color correction, key extraction and motion tracking. \\
\item[YUV-8 bit]
- Allocates 8 bits for Y, U, and V. This is used for low dynamic range operations in which the media is compressed in the YUV color space. Most compressed media is in YUV and this derivative allows video to be processed fast with the least color degradation.
+ Allocates 8\,bits for Y, U, and V. This is used for low dynamic range operations in which the media is compressed in the YUV color space. Most compressed media is in YUV and this derivative allows video to be processed fast with the least color degradation.
\item[YUVA-8 bit]
- Allocates an alpha channel to the 8 bit YUV colormodel for transparency.
+ Allocates an alpha channel to the 8\,bit YUV colormodel for transparency.
+ \end{description}
In order to do effects which involve alpha channels, a colormodel with an alpha channel must be selected.
These are RGBA-8 bit, YUVA-8 bit, and RGBA-Float.
- The 4 channel colormodels are slower than 3 channel colormodels, with the slowest being RGBA-Float.
+ The 4 channel colormodels are slower than 3\,channel colormodels, with the slowest being RGBA-Float.
Some effects, like fade, work around the need for alpha channels while other effects, like chromakey, require an alpha channel in order to be functional.
So in order to get faster results, it is always a good idea to try the effect without alpha channels to see if it works before settling on an alpha channel and slowing it down.
16 bit integers were used in the past and were too lossy and slow for the amount of improvement.
RGB float does not destroy information when used with YUV source footage and also supports brightness above 100\,\%.
Be aware that some effects, like Histogram, still clip above 100\,\% when in floating point.
- \end{description}
+
\item[Interlace mode:]
this is mostly obsolete in the modern digital age, but may be needed for older media such as that from broadcast TV. Interlacing uses two fields to create a frame. One field contains all odd-numbered lines in the image; the other contains all even-numbered lines. Interlaced fields are stored in alternating lines of interlaced source footage. The alternating lines missing on each output frame are interpolated.
\end{description}
projects / goodguy / cin-manual-latex.git / blobdiff