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HelpUpdate : README.video.codec - ascii banner ! + some extra love

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Jerome Blanchi aka d.j.a.y
2019-07-02 20:23:32 +02:00
parent de0da54214
commit 86fc0b5e45
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48
veejay-current/veejay-server/doc/README.video-codec.md
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Video files
=========================
Basic knowledge
@@ -30,7 +42,10 @@ so... Which codec to use ?
-------------
[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.
If you ever want more speed, use AVI `yv16` or `i420` before recording to new samples. Either using console client and **sayVIMS** (`selector 302` _Set codec to use for recording_) or the gui client **Reloaded** [Sample/Stream panel] ---> [Recording to Disk panel] ---> [Codec drop down list].
If you ever want more speed, use AVI `yv16` or `i420` before recording to new samples :
* using console client and **sayVIMS** (`selector 302` _Set codec to use for recording_ (use 'x' to see list))
* from gui client **reloaded** [Sample/Stream panel] ---> [Recording to Disk panel] ---> [Codec drop down list].
### Floss tools that support MJPEG:
* [Cinelerra](http://cinelerra.org/) - Video editing and compositing software
@@ -49,6 +64,7 @@ If you ever want more speed, use AVI `yv16` or `i420` before recording to new sa
Which resolutions to use ?
------------
Veejay can do:
* high resolutions aka HDTV
* pal 16/9 : 1024x576
* pal: 720x576
@@ -64,31 +80,39 @@ How to convert ?
-------------
### You can use FFMpeg
```shell
$ ffmpeg -i input-file -c:v mjpeg -pix_fmt yuvj422p -q:v 1 -an output-file.avi
```
$ ffmpeg -i input-file -c:v mjpeg -pix_fmt yuvj422p -q:v 0 -an output-file.avi
```
Your input video `input-file` will be transcode to `mjpeg` video codec, with a pixel
format `yuvj422p` - color values from 0-255 and only horizontal chroma resolution is halved.
For better performance (but less image accuracy...) you can choose `yuvj420p` , in that
case, both horizontal and vertical chroma resolution are halved. Finally it use a
video quantifier of `1` setting the quality scale (VBR) to best image quality.
In previous example, audio is muted using the `-an` flag, consequently you would start **veejay** with `-a0` to disable audio.
Optionally add PCM 16bit audio, 44.1/48.0 Khz, 2 channels, 8 bits per channel, HD resolution and 25 frames per second.
```
$ ffmpeg -i input-file -c:v mjpeg -s 720p -r 25 -pix_fmt yuvj422p -acodec pcm_s16le -ar 44100 -ac 2 output-file.avi
Optionally add PCM WAVE 16bit audio, 48.0 Khz, 2 channels, 8 bits per channel, HD resolution and 25 frames per second.
```shell
$ 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
```
For more detailled informations concerning audio, look at `README.audio.md`
Check FFmpeg documentation for detailed description of transcoding process and possible customization/automation.
### Or, you can use mplayer
```
```shell
$ mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -o <outputfile> <inputfile>
```
***To scale on the fly, use***
```
```shell
$ mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -vf scale=352:288 -o <outputfile> <inputfile>
```
***Bulk encoding***
A quick hint for bulk encoding a bunch of capture.dv files
```
```shell
$ for i in `ls *dv`;do mencoder -ovc lavc -oac pcm -lavcopts vcodec=mjpeg -o `echo $i | sed s/.dv/.avi/` $i; done;
```
@@ -97,7 +121,7 @@ Consult mplayer documentation about other options, such as cropping and filterin
Going deeper in videos
------------
### What is Dummy mode ?
```
```shell
$ veejay -d
```
@@ -111,8 +135,8 @@ If you use a video file, veejay will take that file's properties as default sett
You can create a fake v4l2 device (`/dev/videoX`), using [v42loopback](https://github.com/umlaeute/v4l2loopback).
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)
```
$ sudo modprobe v4l2loopback
```shell
# modprobe v4l2loopback
$ ffmpeg -f x11grab -r 25 -s 720x576 -i :0.0+5,10 -vcodec rawvideo -pix_fmt yuv422p -f v4l2 /dev/video0
$ veejay -A1 -a0
```