mirror of
https://github.com/game-stop/veejay.git
synced 2025-12-14 20:00:01 +01:00
144 lines
6.1 KiB
Markdown
144 lines
6.1 KiB
Markdown
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| | | | | | \ / [_ | | / / | || \ / [_ / /
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| | | | | | D || _]| O | / / | O || D || _] / /
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| : | | | | || [_ | |/ \_ | || || [_ / \_
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\_/ |____||_____||_____| \___/ \____| \___/ |_____||_____| \____|
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Video files
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=========================
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Basic knowledge
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--------
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A video file consist out of two SEPARATE elements:
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- container
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- codec
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The container holds the digitally encoded data and the codec is capable of decoding/encoding this digitally encoded data.
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### Veejay's file format support
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Veejay supports the AVI and the Quicktime container, with the following codecs:
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- **Quicktime**
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- mpjeg,mjpa,jpeg,dmb1,mpng,png
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- dvsd, dv, dvcp, dvhd
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- **AVI**
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- mjpeg, mjpa,jpeg,jfif,dmb1,mpng,png
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- dvsd, dv, dvcp, dvhd
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- i420, i422, yv16, hfyu
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- **Raw DV**
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- PAL / NTSC dvsd
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**Important:** Veejay **can only deal** with video files that consists entirely out of whole images, **only I-frames**.
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You can also load mime type `image/jpeg` images ( .jpg, .jpeg, .JPG, .JPEG)
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so... Which codec to use ?
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-------------
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[MotionJPEG](https://en.wikipedia.org/wiki/Motion_JPEG) (mjpeg) is the veejay codec of choice for most applications, it gives you a good tradeof between compression, quality and compatibility. M-JPEG is an intraframe-only compression, each video frame is coded separately as a JPEG image, giving advantage of rapidly changing motion in the video stream.
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If you ever want more speed, use AVI `yv16` or `i420` before recording to new samples :
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* using console client and **sayVIMS** (`selector 302` _Set codec to use for recording_ (use 'x' to see list))
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* from gui client **reloaded** [Sample/Stream panel] ---> [Recording to Disk panel] ---> [Codec drop down list].
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### Floss tools that support MJPEG:
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* [Cinelerra](http://cinelerra.org/) - Video editing and compositing software
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* [Kdenlive](https://kdenlive.org/fr/) - Video editing software
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* [Shotcut](https://shotcut.org/) - Video editing software
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* [MJPEG Tools](http://mjpeg.sourceforge.net/) - Set of tools for videos recording and playback
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* [Mplayer, and mencoder](http://www.mplayerhq.hu/) - Movie player which runs on many systems
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* [FFmpeg](https://ffmpeg.org) - Vast suite of libraries and programs for handling video, audio, and other multimedia files and streams
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* [Libav](https://libav.org) - FFmpeg fork, has a second choice
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* [VLC ](https://www.videolan.org/) - Media player, streaming media server and more...
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* [Lives](http://lives-video.com/) - VJ and Video Editing system
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* [Kino](http://www.kinodv.org/Kino) (_not been actively maintained since 2009_)
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* [Linux Video Studio](http://ronald.bitfreak.net/lvs/index.shtml) (_not actively maintained_)
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Which resolutions to use ?
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------------
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Veejay can do:
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* high resolutions aka HDTV
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* pal 16/9 : 1024x576
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* pal: 720x576
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* ntsc: 720x480
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* 1/4 pal: 360x288
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* 1/4 ntsc: 360x240
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In fact pretty much any resolution divisible by 8, which is a limitation for some video internals (encoders and effects). Finally it is an everyone finding balance between preciseness of graphics, complexity of effect's chain and necessary resources for a realtime accuracy.
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If you load multiple video files **on the command line**, make sure that all files have the same resolution and audio properties.
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How to convert ?
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-------------
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### You can use FFMpeg
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```shell
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$ ffmpeg -i input-file -c:v mjpeg -pix_fmt yuvj422p -q:v 1 -an output-file.avi
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```
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Your input video `input-file` will be transcode to `mjpeg` video codec, with a pixel
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format `yuvj422p` - color values from 0-255 and only horizontal chroma resolution is halved.
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For better performance (but less image accuracy...) you can choose `yuvj420p` , in that
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case, both horizontal and vertical chroma resolution are halved. Finally it use a
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video quantifier of `1` setting the quality scale (VBR) to best image quality.
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In previous example, audio is muted using the `-an` flag, consequently you would start **veejay** with `-a0` to disable audio.
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Optionally add PCM WAVE 16bit audio, 48.0 Khz, 2 channels, 8 bits per channel, HD resolution and 25 frames per second.
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```shell
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$ ffmpeg -i input-file -q:v 1 -c:v mjpeg -s 720p -r 25 -pix_fmt yuvj422p -acodec pcm_s16le -ar 48000 -ac 2 output-file.avi
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```
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For more detailled informations concerning audio, look at `README.audio.md`
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Check FFmpeg documentation for detailed description of transcoding process and possible customization/automation.
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### Or, you can use mplayer
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```shell
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$ mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -o <outputfile> <inputfile>
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```
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***To scale on the fly, use***
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```shell
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$ mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -vf scale=352:288 -o <outputfile> <inputfile>
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```
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***Bulk encoding***
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A quick hint for bulk encoding a bunch of capture.dv files
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```shell
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$ for i in `ls *dv`;do mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -o `echo $i | sed s/.dv/.avi/` $i; done;
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```
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Consult mplayer documentation about other options, such as cropping and filtering out blocks in video.
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Going deeper in videos
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------------
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### What is Dummy mode ?
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```shell
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$ veejay -d
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```
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Dummy mode opens up a 'color stream' to start veejay without a video file.
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If you use a video file, veejay will take that file's properties as default settings for the whole session.
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### Virtual video device
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You can create a fake v4l2 device (`/dev/videoX`), using [v42loopback](https://github.com/umlaeute/v4l2loopback).
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Setup a single virtual video device on `/dev/video0` (assuming that it does not previously exist), stream some screen capture to it and open veejay using this source (audio disabled)
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```shell
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# modprobe v4l2loopback
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$ ffmpeg -f x11grab -r 25 -s 720x576 -i :0.0+5,10 -vcodec rawvideo -pix_fmt yuv422p -f v4l2 /dev/video0
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$ veejay -A1 -a0
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```
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Here, `0.0` is `display.screen` number of your X11 server, same as the DISPLAY environment variable and `5` is the x-offset and `10` the y-offset for the grabbing.
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