\section{Hardware video acceleration}%
\label{sec:hardware_video_acceleration}
+\index{hardware!acceleration}
With certain newer, more powerful graphics boards and newer device drivers, there is the potential for enhanced \textit{decode} and \textit{encode} performance. Decode refers to loading and playing video in \CGG{}. The GPU, Graphics Processing Unit, on the graphics board is accessed via one of the following libraries: vdpau or vaapi. The hardware acceleration done by the graphics card increases performance by activating certain functions in connection with a few of the FFmpeg decoders. This use makes it possible for the graphics card to decode video, thus offloading the CPU. Decode operations are described here next.
Encode refers to rendering video and is described at the end of this section
\subsection{GPU hardware decoding}%
\label{sub:gpu_hardware_decoding}
+\index{hardware!decoding}
\begin{enumerate}
\item Verify that you have installed \textit{libva-dev} or \textit{libva} on your operating system.
can not convert the data, you will see the error message of \textit{Error retrieving data from GPU to CPU}.
\end{enumerate}
-Due to variations in user’s computer hardware configuration, it is often suggested that you refer to your startup window to check for error messages. Since your situation is unique, the error may not have been seen by anyone else and is probably unknown/undocumented.
+AppImage does not provide this capability. Due to variations in user’s computer hardware configuration, it is often suggested that you refer to your startup window to check for error messages. Since your situation is unique, the error may not have been seen by anyone else and is probably unknown/undocumented.
\textcolor{red}{For debugging problems, modify in the \CGG{} ffmpeg subdirectory, the file: \texttt{decode.opts} by temporarily changing the line from \textit{loglevel =fatal} to \textit{loglevel =verbose} and restarting \CGG{}}.
\subsubsection*{Possible improvements or differences}%
\subsubsection*{Special .opts file}%
\label{ssub:special_opts_file}
+\index{hardware!special opts files}
The situation may arise where you have enabled hardware acceleration and after loading several files for a project, you find that a file had some kind of error resulting in a black video instead of an image or you see an error message pop up which states something like \textit{Error retrieving data from GPU to CPU} or \textit{err: Unknown error occurred}. Because the \texttt{CIN\_HW\_DEV} environment variable is either all or none, ordinarily in order to correct the non-working video you would have to turn off hardware acceleration for the entire project/session. However, there is a way to continue working on your project without having to reload all of your files. You still use the environment variable and it will be effective for all of the formats it is able to handle, but you make an exception for any of the files that erred out. To do this you simply create a file in the same directory with the same name as the erring file with the different extension of .opts. The contents of this .opts file would just be the one line of:
HEVC with NVIDIA, VDPAU driver is buggy, skipping
\end{lstlisting}
-If you would like to see more information on what is occurring, you can modify in the \CGG{} ffmpeg subdirectory, the file: \texttt{decode.opts} by temporarily changing the line from \textit{loglevel =fatal} to \textit{loglevel =verbose} and restarting \CGG{}. Then you will see messages in the startup window like:
+AppImage does not provide this capability. If you would like to see more information on what is occurring, you can modify in the \CGG{} ffmpeg subdirectory, the file: \texttt{decode.opts} by temporarily changing the line from \textit{loglevel =fatal} to \textit{loglevel =verbose} and restarting \CGG{}. Then you will see messages in the startup window like:
\begin{lstlisting}[numbers=none]
[AVHWDeviceContext @ 0x7fc9540be940] Successfully created a VDPAU device
\subsection{GPU hardware encoding}%
\label{sub:gpu_hardware_encoding}
+\index{hardware!encoding}
Encoding using hardware acceleration of your graphics board GPU is
included in \CGG{} but it is of limited availability and works only
\subsubsection*{Broadcom, Intel HD, AMD}%
\label{ssub:broadcom_intel_amd}
+\index{hardware!vaapi}
To use hardware acceleration for rendering (that is, encoding) you do not have to set a preference or an environment variable, as was required for decoding. To use this feature you use an ffmpeg render options file which specifies a vaapi codec, such as h264\_vaapi. You must include this line in that options file to trigger the hardware probe: \qquad \texttt{CIN\_HW\_DEV=vaapi}
\subsubsection*{Nvidia graphics boards}%
\label{ssub:nvidia_graphics_card}
+\index{hardware!nvenc}
To use hardware acceleration for rendering (that is, encoding) you do not have to set a preference or an environment variable, as was required for decoding. To use this feature you use an ffmpeg render options file which specifies the nvenc codec, either \texttt{h264\_nvenc.mp4} or \texttt{nvenc.mp4}. There are several requirements in order for this to work on your computer as listed here:
\subsection{Effects (OpenCL, Cuda)}%
\label{sub:effects_opencl_cuda}
+\index{openCL}
+\index{CUDA}
CUDA® is a parallel computing platform / programming model developed by Nvidia that provides big increases in computing performance through use of the GPU. It was first introduced in about 2006 for applications in computationally intense fields such as astronomy, biology, chemistry, and physics.
\section{Optimized Playback -- X11 Direct}%
\label{sec:optimized_playback}
+\index{playback -X11 direct}
Normally, when \CGG{} reads a video frame, it is copied into a \textit{Vframe}. This frame may also need other actions performed on it, such as a color model change. In addition, ffmpeg and libzmpeg \textit{can\_scale\_input}. So the read can be color transformed and scaled just by asking the library to do that. This means that if the compositor is in a \textit{good} state with no zoom, the VFrame read can be done in the fastest render color model, and already scaled to the correct size for the compositor. In reality, this is not what you need for editing, but quite often the \textit{virtualconsole} is not used because the render is media only -- that is \textit{just data}. If no data transforms are needed and the input scaling can be done, the vrender program detects this, and tells the codec to transmit the data in a compatible way to the compositor canvas. This is the \textit{X11 direct} data path.
\section{Proxy Settings and Transcode}%
\label{sec:proxy_settings}
-Info on proxies in \nameref{sec:proxy}
+Information on proxies to reduce required CPU for less powerful computers is in the section \nameref{sec:proxy}.
-Info on transcode in \nameref{sec:transcode}
+Information on transcode which is used to provide keyframes to make the video seekable is in the section \nameref{sec:transcode}.
\section{Some Settings Parameter Values}%
\label{sec:settings_parameter_values}
+\index{cache}
\texttt{Cache} in \texttt{Settings $\rightarrow$ Preferences, Performance} tab is used to store images on the timeline. One 1080p frame uses about 10 MB. The default setting is 256 and this is enough for testing and running. However, why not use more memory if it is available. To experiment for testing a good number tuned to the way you use your computer, set the cache to 0, start up \CGG{}, load a typical media file, play it and run \texttt{top} on the command line in another window to see how much memory is being used. In the \textit{top} display, look at \textit{free} memory. Whatever your computer is not using, is a good number to use for cache. If you start other programs, or change the design of the session so that it uses a lot of frame storage, you may need to experiment again later and resize accordingly.
\item For large media files, use proxy to do your main editing.
\item In \texttt{Settings $\rightarrow$ Preferences, Appearance} tab, uncheck \textit{Use thumbnails in resource window}.
\item In \texttt{Settings $\rightarrow$ Preferences, Appearance} tab, uncheck \textit{Autocolor assets}.
- \item Speed-up certain time-consuming FFmpeg plugins through use of a carefully selected \texttt{.opts} file.
+ \item Speed-up certain time-consuming FFmpeg plugins through use of a carefully selected \texttt{.opts} file. See \nameref{sub:speedup_ffmpeg_plugin_opts}
\item For large media files, in \texttt{Settings $\rightarrow$ Preferences, Playback A}, Video Driver set \textit{use direct X11 render if possible}.
\item For the Video Driver in \texttt{Settings $\rightarrow$ Preferences, Playback A}, if using a good graphics card, choose \textit{X11-OpenGL}.
\item Set \textit{CIN\_HW\_DEV=vdpau} or \textit{vaapi} to use the graphics GPU for certain ffmpeg media decoding.
\section{General Crash Handling Tips}%
\label{sec:general_crash_tips}
+\index{crash handling tips}
This section is a handy guide for describing various kinds of software computer system failures. Only some of these various lockups or crashes can be dealt with. Hopefully, it will help to have some hints to know what kind of failure it is, or to save your work or to avoid future problems. For most of this, your user name must be root, although you can certainly try to see if it works for you when not root.
\subsection{Camera supplied LUTs}%
\label{sub:camera_supplied_luts}
+\index{LUT}
A LUT, acronym for Look-Up Table, is a mathematically precise way of taking specific RGB image values from a source image and modifying them to new RGB values by changing the hue, saturation and brightness values of that source image. In other words, LUTs are used to map one color space to another. Some high-end cameras supply a .cube file to use as input. There are several different ffmpeg plugins included with CinGG for using Lut's. These are:
\subsection{Encoding into Dolby Pro Logic}%
\label{sub:encoding_dolby_pro_logic}
+\index{dolby pro logic}
Dolby pro logic is an easy way to output 6 channel audio from a 2-channel soundcard with degraded but useful results. Rudimentary Dolby pro logic encoding can be achieved with usage of some effects.
\subsection{Remove Interlacing}%
\label{sub:remove_interlacing}
+\index{interlacing}
Interlacing often exists on older video sources, such as camcorders, and was previously used in broadcast television. Playing this video results in jagged images on a computer monitor, but with \CGG{} you can use deinterlacing effects to solve this. After some experimentation, it has been determined that the FFmpeg \textit{F\_kerndeint} plugin seems to produce the best results with the least amount of fiddling. But some of the parameters described next are pertinent to other potential plugin usage.
\begin{description}
\item[Line Doubling:] done by the \textit{Deinterlace} effect when set to \textit{Odd} lines or \textit{Even} lines. When applied to a track it reduces the vertical resolution by $\frac{1}{2}$ and gives you progressive frames with stairstepping. This is only useful when followed by a scale effect which reduces the image to half its size.
\item[Line averaging:] the \textit{Deinterlace} effect when set to \textit{Average even} lines or \textit{Average odd} lines does exactly what line doubling does except instead of making straight copies of the lines, it makes averages of the lines. This is actually useful for all scaling.
- \item[Inverse Telecine:] this is the most effective deinterlacing tool when the footage is an NTSC TV broadcast of a film. It is described in Effect Plugins (\ref{sub:inverse_telecine}), chapter 10.
+ \item[Inverse Telecine:] this is the most effective deinterlacing tool when the footage is an NTSC TV broadcast of a film. It is described in Effect Plugins (\ref{sub:inverse_telecine}).
\item[Time base correction:] the previously discussed three tools either destroy footage irreversibly or do not work at times. Time base correction may be a better tool to use because it leaves the footage intact. It does not reduce resolution, perceptually at least, and does not cause jittery timing.
- \item[Frames to Fields effect:] converts each frame to two frames, so it must be used on a timeline whose project frame rate is twice the footage's frame rate. In the first frame it puts a line-averaged copy of the even lines. In the second frame it puts a line-averaged copy of the odd lines. When played back at full framerate it gives the illusion of progressive video with no loss of detail. This effect can be reversed with the \textit{Fields to Frames} effect, which combines two frames of footage back into the one original interlaced frame at half the framerate. However, keep in mind that Frames to Fields inputs frames at half the framerate as the project. Effects before Frames to Fields process at the reduced framerate. The output of Frames to Fields can not be compressed as efficiently as the original because it introduces vertical twitter and a super high framerate. Interlaced $29.97$ fps footage can be made to look like film by applying Frames to Fields and then reducing the project frame rate of the resulting $59.94$ fps footage to $23.97$ fps. This produces no timing jitter and the occasional odd field gives the illusion of more detail than there would be if you just line averaged the original. It is described in Effect Plugins (\ref{sub:frames_to_fields}), chapter 10.
+ \item[Frames to Fields effect:] converts each frame to two frames, so it must be used on a timeline whose project frame rate is twice the footage's frame rate. In the first frame it puts a line-averaged copy of the even lines. In the second frame it puts a line-averaged copy of the odd lines. When played back at full framerate it gives the illusion of progressive video with no loss of detail. This effect can be reversed with the \textit{Fields to Frames} effect, which combines two frames of footage back into the one original interlaced frame at half the framerate. However, keep in mind that Frames to Fields inputs frames at half the framerate as the project. Effects before Frames to Fields process at the reduced framerate. The output of Frames to Fields can not be compressed as efficiently as the original because it introduces vertical twitter and a super high framerate. Interlaced $29.97$ fps footage can be made to look like film by applying Frames to Fields and then reducing the project frame rate of the resulting $59.94$ fps footage to $23.97$ fps. This produces no timing jitter and the occasional odd field gives the illusion of more detail than there would be if you just line averaged the original. It is described in Effect Plugins (\ref{sub:frames_to_fields}).
\item[HDTV exceptions:] $1920\times1080$ HDTV is encoded in a special way. If it is a broadcast of original HDTV film, an inverse telecine works. But if it is a rebroadcast of a $720\times480$ source, you need to use a time base and line doubling algorithm to deinterlace it.
\end{description}
\subsection{Time stretching audio}%
\label{sub:time_stretching_audio}
+\index{audio!time stretching}
It may appear that time stretching audio is a matter of selecting a region of the audio tracks, enabling recording for the desired tracks, going to\texttt{ Audio $\rightarrow$ Render Effect}, and applying \textit{TimeStretch}. In actuality there are 3 audio effects for time stretching: Time Stretch, Resample, and Asset info dialog.
You can see that the camera smoothly flows from keyframe point to next keyframe point, as \CGG{} automatically adjusts the camera movement in straight lines from point to point.
+\subsection{Video lagging behind Audio}%
+\label{sub:video_lagging}
+
+When there is a lag between the Audio and the Video, it can be because there are a lot of video frames
+and the computer can not display them as fast as the Audio can play the samples. However, this does
+not affect the rendered media in that the Audio and Video will be correctly synchronized. When playing
+the original media, you can alleviate the lag between the Audio and Video by disabling
+\textit{Play every frame} in \texttt{Settings $\rightarrow$ Preferences, Playback A} tab. Now frames
+will be skipped in order to keep the audio/video in synch.
projects / goodguy / cin-manual-latex.git / blobdiff