Before reading trying to use video inputs, you should read and understand how
themes work in general (see :doc:`theme`). Video inputs are available from
-Nageru 1.6.0 onwards. There is currently no support for audio from video inputs;
-all videos are silent. (This may change in the future.) If a file contains
-multiple video streams, like different angles or resolutions, only the first
-will be used.
+Nageru 1.6.0 onwards, and from Nageru 1.7.2, you can get audio from video inputs
+like any other input. (Be advised, though, that making a general video player
+that can maintain A/V sync on all kinds of video files is a hard problem,
+so there may still be bugs in this support.)
+
+If a file contains multiple video streams, like different
+angles or resolutions, only the first will be used. Similarly, only the first
+audio stream is used, and it's always converted to 48 kHz stereo.
Basic video inputs
This will make it play at twice its usual speed. Your rate should not be
negative nor exactly zero. You can set a rate to e.g. 1e-6 if you want to
in practice stop the video; once you change it back to normal speed,
-the next frame will resume playing.
+the next frame will resume playing. Be aware that changing the rate may
+make the audio behave unpredictably; there are no attempts to do time
+stretching or change the pitch accordingly.
+
+Finally, if you want to forcibly abort the playing of a video,
+even one that is blocking on I/O, you can use (since Nageru 1.7.2)::
+
+ video:disconnect()
+
+This is particularly useful when dealing with network streams, as FFmpeg does not
+always properly detect if the connection has been lost. See :ref:`menus`
+for a way to expose such functionality to the operator.
+
+.. _subtitle-ingest:
+
+Ingesting subtitles
+-------------------
+
+Video streams can contain separate subtitle tracks. Since Nageru 1.8.1,
+you can read these streams. This is particularly useful when using Nageru
+and Futatabi together (see :ref:`talkback`).
+
+To get the last subtitle given before the current video frame, call
+“signals:get_last_subtitle(n)” from get_chain, where n is the signal number
+of your video signal. It will either contain nil, if there hasn't been
+a subtitle, or else the raw subtitle. Note that if the video frame and
+the subtitle occur on the exact same timestamp, and the video frame
+is muxed before the subtitle packet, the subtitle will not make it in time.
+(Futatabi puts the subtitle slightly ahead of the video frame to avoid this.)
Integration with CasparCG
-------------------------
-`CasparCG <http://casparcg.com/>`_ is an open-source broadcast graphics system,
-originally written by SVT, the Swedish public TV broadcaster. (In this
-context, “graphics” refers mostly to synthetically generated content,
-such as the score box in a sporting match.) With some coaxing, it is possible
-to integrate CasparCG with Nageru, so that Nageru does the mixing of the video
-sources and CasparCG generates graphics—CasparCG can also work as a standalone
-mixer indepedently of Nageru, but this will not be covered here.
-
-The most straightforward use of CasparCG is to use it to generate an overlay,
-which is then taken in as a video input in Nageru. To achieve this, the simplest
-solution is to send raw BGRA data over a UNIX domain socket [#rawvideo]_, which involves
-adding an FFmpeg output to your CasparCG configuration. This can either be done
-by modifying your casparcg.config to open up a socket in your home directory
-(you shouldn't use /tmp on a multi-user machine, or you may open up a security
-hole)::
-
- <consumers>
- <ffmpeg>
- <device>1</device>
- <path>unix:///home/user/caspar.sock</path>
- <args>-c:v rawvideo -vf format=pix_fmts=bgra -f nut -listen 1</args>
- </ffmpeg>
- <system-audio></system-audio>
- </consumers>
-
-or by setting it up on-the-fly through ACMP::
-
- add 1 stream unix:///home/user/caspar.sock -c:v rawvideo -vf format=pix_fmts=bgra -f nut -listen 1
-
-You can then use *unix:///home/user/caspar.sock* as a video input to Nageru on the
-same machine, and then use e.g. *OverlayEffect* to overlay it on your video chains.
-(Remember to set up the video as BGRA and not Y'CbCr, so that you get alpha.)
-
-CasparCG and Nageru does not run with synchronized clocks, so you will not get
-frame-perfect synchronization between graphics and overlay; however, this is normal
-even in a hardware chain, and most overlay graphics does not need to be timed
-to the input more than through a few frames. However, note that it is possible
-that Nageru lags behind CasparCG's graphics production after a while (typically
-on the order of hours) due to such clock skew; the easiest solution to this is
-just to use *change_rate(2.0)* or similar on the input, so that Nageru will consume
-CasparCG's frames as quickly as they come in without waiting any further.
-
-There's also one usability stumbling block: *CasparCG's FFmpeg
-streams are one-shot, and so are FFmpeg's UNIX domain sockets.* This means that,
-in practice, if Nageru ever disconnects from CasparCG for any reason, the socket
-is “used up”, and you will need to recreate it somehow (e.g., by restarting CasparCG).
-Also note that the old socket still lingers in place even after being useless,
-so you will *first* need to remove it, and CasparCG does not do this for you.
-The simplest way to deal with this is probably to have a wrapper script of some
-sort that orchestrates Nageru, CasparCG and your client for you, so that everything
-is taken up and down in the right order; it may be cumbersome and require some
-tweaking for oyur specific case, but it's not a challenging problem per se.
-
-Nageru does not have functionality to work as a CasparCG client in itself,
-nor can your theme present a very detailed UI to do so. However, do note that
-since the theme is written in unrestricted Lua, so you can use e.g.
-`lua-http <https://github.com/daurnimator/lua-http>`_ to send signals
-to your backend (assuming it speaks HTTP) on e.g. transition changes.
-With some creativity, this allows you to at least bring some loose coupling
-between the two.
-
-In general, the integration between Nageru and CasparCG leaves a bit to be
-desired, and in general, the combination of CasparCG + Nageru will require
-a beefier machine than Nageru alone. However, it also provides a much richer
-environment for graphics, so for many use cases, it will be worth it.
-
-.. [#rawvideo] Good video codecs that support alpha are rare, so as long as CasparCG
- and Nageru are running on the same machine, raw video is probably your
- best bet. Even so, note that FFmpeg's muxers are not really made for
- such large amounts of data that raw HD video produces, so there will
- be some performance overhead on both sides of the socket.
+This section has been removed, as since 1.7.0, Nageru has :doc:`native support for HTML5 inputs <html>`,
+obsoleting CasparCG integration.
projects / nageru-docs / blobdiff