-\section{Webm\,/\,Vp9 Usage and Example File\protect\footnote{credit Frederic Roenitz}}%
-\label{sec:webm/vp9_usage_example}
-
-\textsc{VP9} is a video codec licensed under the BSD license and is
-considered open source,
-% Sisvel Announces AV1 Patent Pool, March 10, 2020
-% https://www.streamingmedia.com/Articles/ReadArticle.aspx?ArticleID=139636
-% Webm / VP9 is a media file format which is free to use under the
-% BSD license and is open-source; thus there are no licensing
-% issues to be concerned about.
-the \textsc{Webm} container is based on \textsc{Matroska} for video
-and \textsc{Opus} for audio. There are some common \textsc{VP9} rendering
-options files that support creation of video for YouTube,
-Dailymotion, and other online video services.
-
-YouTube easy startup steps are documented in the Appendix (\ref{sec:youtube_with_cinelerra}). These same steps have been verified to work for creating Dailymotion videos -- however, the created files must be renamed before uploading to change the youtube extension to webm instead for Dailymotion.
-
-Below is one of the \textsc{VP9} rendering options file with documentation for specifics:
-
-\textbf{webm libvpx-vp9}
-
-(20171114-2203)
-
-from {\small \url{https://developers.google.com/media/vp9/settings/vod/}}
-
-1280x720 (24, 25 or 30 frames per second)
-
-Bitrate (bit rate)
-
-\textsc{VP9} supports several different bitrate modes:
-
-\textit{mode:}
-
-\begin{tabular}{p{6cm} p{10cm}}
- Constant Quantizer (Q) & Allows you to specify a fixed quantizer value; bitrate will vary \\
- Constrained Quality (CQ) & Allows you to set a maximum quality level. Quality may vary within bitrate parameters\\
- Variable Bitrate (VBR) & Balances quality and bitrate over time within constraints on bitrate\\
- Constant Bitrate (CBR) & Attempts to keep the bitrate fairly constant while quality varies\\
-\end{tabular}
-
-CQ mode is recommended for file-based video (as opposed to streaming). The following FFMpeg command-line parameters are used for CQ mode:
-
-\textit{FFMpeg}:
-
-\begin{center}
- \begin{tabular}{{p{4cm} p{10cm}}}
- -b:v <arg> & Sets target bitrate (e.g. 500k)\\
- -minrate <arg> & Sets minimum bitrate.\\
- -maxrate <arg> & Sets maximum bitrate.\\
- -crf <arg> & sets maximum quality level. Valid values are 0-63, lower numbers are higher quality.\\
-\end{tabular}
-\end{center}
-
-\textit{Note 1}: Bitrate is specified in kbps, or kilobits per second. In video compression a kilobit is generally assumed to be 1000 bits (not 1024).
-
-\textit{Note 2:} Other codecs in FFMpeg accept the \textit{-crf} parameter but may interpret the value differently. If you are using \textit{-crf} with other codecs you will likely use different values for VP9.
-
-\texttt{bitrate=1024k}\\
-\texttt{minrate=512k}\\
-\texttt{maxrate=1485k}\\
-\texttt{crf=32}
-
-\textit{Tiling} splits the video into rectangular regions, which allows multi-threading for encoding and decoding. The number of tiles is always a power of two. 0=1 tile; 1=2; 2=4; 3=8; 4=16; 5=32\\
-\texttt{tile-columns=2}
-
-(modified from {\small \url{https://trac.ffmpeg.org/wiki/EncodingForStreamingSites}})
-
-To use a 2 second \textit{GOP} (Group of Pictures), simply multiply your output frame rate $\times$ 2. For example, if your input is \textit{-framerate 30}, then use \textit{-g 60}.\\
-\texttt{g=240}
-
-number of \textit{threads} to use during encoding\\
-\texttt{threads=8}
-
-\textit{Quality} may be set to good, best, or realtime\\
-\texttt{quality=good}
-
-\textit{Speed}: this parameter has different meanings depending upon whether quality is set to good or realtime. Speed settings 0-4 apply for VoD in good and best, with 0 being the highest quality and 4 being the lowest. Realtime valid values are 5-8; lower numbers mean higher quality\\
-\texttt{speed=4}