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Video Output (Rendering)

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xSTUDIO allows you to render Playlists, Subsets, Contact Sheets and Timelines to a containerised media file (mp4, mov, mkv, webm etc.) using the various video and audio codecs available through the popular FFMpeg application. You can select one or more items in the Playlists pane to render and then right mouse click to get the context menu (or go via the main File menu) and choose Export->Render Selected Item(s) to Movie …/

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+Export to movie menu +
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Use the context menu or File menu to launch the render wizard.

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You will then see get the Render Video dialog where you can specify the format of your output video.

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+Render Video dialog +
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The Render Video allows you to fully specify your output video.

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What gets Rendered

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What gets rendered depends on the type of item that you have selected according to these simple rules:

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  • Playlistst and Subsets: All of the media items within the Playlist or Subset are ‘strung’ together in a linear sequence reflecting the ordering of the media in the Playlist or Subset. Thus if you have 10 video files in a Playlist the output render will show each of the 10 clips in sequence, and every frame in each video file being used.

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  • Contact Sheets: A contact sheet will render exactly as it appears in the xSTUDIO UI, with the same layout (e.g. Grid mode) and the same duration as the corresponding playhead for the source Contact Sheet.

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  • Sequences (Timelines): A sequence will render out exactly as it appears in the xSTUDIO Session, so track visibility, clip visibility and the Compare Mode will also be respected. Thus, for example, you can render out 4 video tracks in a 2x2 arrangement by setting the compare mode to ‘Grid’ before selecting the sequence for rendering.

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Note

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Overlay graphics like annotations and HUD items (like media metadata overlays) are included in the renders as long as they are enabled in the main xSTUDIO interface. Important: if you switch off the HUD in the xSTUDIO main interface while a render is in-progress then the HUD will also vanish from the render at whatever point the renderer was at when the HUD was disabled. Therefore, do not adjust the HUD settings while renders are in-progress!

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Render Output Settings

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Executing, Monitoring and Checking a Render

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Once you have supplied a filesystem path for your output the ‘Render’ button will then become clickable and you can dispatch the job to the render queue. Note that you can queue up multiple renders at once - if you have multiple items selected in the Playlist panel the Render Dialog will refresh for the next item when you hit the Render button. Use the ‘Skip’ button to skip a Playlist item and configure the next selected item for rendering.

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Note

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The xSTUDIO output rendering feature works entirely in the background and you can continue using the xSTUDIO interface while renders are in progress. On some systems with plenty of RAM, a modern GPU and a high spec CPU then you may not even see any noticeable effect on xSTUDIO’s performance while it is rendering and you can continue playing and reviewing media.

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Note

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When a render is queued, a complete and exact copy of the Playlist, Subset, Contact Sheet or Sequence is created under-the-hood. This means that if you make changes to the Playlist etc. after it has been queued, or even delete it from the session, the render will not be affected.

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On hitting the ‘Render’ button a render status button will appear to the top right of the Playlists panel which looks like this:

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+Render Video dialog +
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The movie button with animated highlight tells us that xSTUDIO is rendering.

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Now, you can click on this button to view the render queue. xSTUDIO will render one output at a time and work through the queue in the order that you dispatched them.

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+Render Queue +
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The render queue interface. Accessed this by clicking on the movie button that appears to the top right of the Playlists panel.

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When a job is complete, you can move the mouse over the green tick icon to get a ‘play’ button. Click on this and a Quick View window will be opened with the rendered output for you to check immediately. Failed renders are indicated by the red warning icon. The button with the monitor hearbeat icon can be clicked to see the full FFMpeg log both during the render and when it’s complete or, most usefully, if a render fails. Renders can be cancelled before they start or when they are in progress with the trashcan button, which will also clear successfully completed renders from the queue.

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Output Video and Audio Codec Settings

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How the Renderer Works

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Before getting into codecs it’s useful to know how xSTUDIO’s renderer works. During the render xSTUDIO generates image frames using an off-screen Viewport and the image data is written into a virtual file called a ‘pipe’. This is done in a background process so that the xSTUDIO interface does not freeze. An instance of the famous media encode/decode application FFMpeg is also started up by xSTUDIO in the background. This FFMpeg process is set up to receive the images (and audio samples) from xSTUDIO via the pipe. The important thing for the user to know is that the parameters that are passed to FFMpeg when it starts up can be configured by the user via FFMpeg’s command line interface. As such, you have total freedom to set-up the video and audio codecs and their tuning parameters used to create the output file - you simply specify the encoding parameters exactly as if you were running FFMpeg in a terminal.

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Configuring Encoding Presets

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The Render Video dialog provides a drop-down list of video & audio codec presets. Next to this is a pen icon. Click this to access the video codec presets panel.

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+Render Queue +
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The FFMpeg encode presets panel.

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This panel allows you to specify the exact FFMpeg output parameters for the video and audio encoding. The existing presets (which are read-only, and therefore greyed out in the list) can serve as useful reference if you wish to add your own new presets. FFMpeg has an almost limitless number of codec options and special filters that you can supply to tune the video encoding and we do not provide any documentation here. Luckily there are loads of question and answers on the web about how to use and optimise FFMpeg to get particular outputs so it’s not too hard to find the settings that you need. Audio encoding options are specified in a separate column and similar principles apply: many encoding settings are possible and it’s crucial to set these correctly for successful video generation. Note that if you do not render audio (by unchecking the ‘Render Audio’ box in the main video render dialog) the audio encode options can be left blank.

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There is also a bit depth drop-down setting. This sets the colour resolution of the RGB image that xSTUDIO pipes to FFMpeg - 16 bits is more accurate and is needed if you are outputting a video format like ProRes that has 10 bit or 12 bit bit depth. For many other formats where your output has only 8 bits per channel, selecting 8 bits for the source image will result in much shorter render times without affecting the quality.

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Note

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An output pixel format (-pix_fmt option) should be specified explicitly in your video encode presets. This is because FFMpeg will otherwise try and pass through the input pixel format (Which is rgba) and this is not compatible with most video encoders.

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Troubleshooting

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If you add new encoding presets and find that your render fails when you use them you will need to debug the settings. Via the Render Queue interface, you can access the FFMpeg output log for the failed render via the heartbeat monitor button. Look very carefully at FFMpeg’s log - it can sometimes be hard to spot but you should be able to see what the error was so that you can go back and tweak your presets until the render goes through.

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