====== Multimedia encoding ======

===== Images =====

==== convert ====
=== size operations ===

  * resize: scale image<code>
convert in.png -resize 640x480 out.png
</code>
  * crop: crop image<code>
convert in.png -crop 640x480+10+10 out.png
</code>
  * extent: add margins or crops<code>
convert in.png -gravity center -extent 1420x1420       out.png
convert in.png                 -extent 1420x1420-10-10 out.png
</code>

=== Annotate an image with text ===
Simple text:
<code>
convert in.png \
  -pointsize 20 -fill red -draw 'text 10,30 "My text" ' \
  out.png
</code>

Text with shadow:
<code>
convert in.png \
  -gravity SouthEast \
  -stroke '#000C' -strokewidth 2 -annotate 0 "My text" \
  -stroke none    -fill white    -annotate 0 "My text" \
  out.png
</code>

=== Append images ===

<code>
convert in1.png in2.png +append out.png # horizontally
convert in1.png in2.png -append out.png # vertically
</code>

More complex:
<code>
convert im1.png -resize 640x480 ppm:- \
	| convert im2.png - +append ppm:- \
		| convert im3.png - -append final.png
</code>

=== Create animated GIF ===

<code>convert -delay 50 -loop 0 *.jpg out.gif</code>

=== Formats ===
  * EPS to RGB:<code>
convert -density 600x600 -flatten -depth 8 -colorspace RGB file.eps ppm:- | convert - file.png
</code>

==== Exif ====
=== exiftool ===
  * restore exif Orientation tag: if you have photos captured with a device that sets the orientation tag, but you used a viewer that doesn't use this tag, and rotated the image with a software that doesn't update this tag, then the image is inconsistent and is not well displayed in exif-aware viewers. To reset the orientation tag, you can use the following command:<code>
exiftool -overwrite_original -Orientation="Horizontal (normal)" <file>
</code>


===== Video =====
==== mencoder ====
(comes with mplayer).

[[http://gentoo-wiki.com/HOWTO_Mencoder_Introduction_Guide]]

General syntax:
<code bash>
mencoder \
  <input data> \
  <input options> \
  <output options> \
  <output data>
</code>

=== Input data and options ===
  * Video files<code>
mencoder \
  <input_file_1> <input_file_2> ... \
  <input options> \
  <output options> \
  <output data>
</code>

  * Image files<code>
mencoder \
  "mf://img.o.*.PNG" \
  -mf fps=25 \
  <output options> \
  <output data>
</code>

  * Image files from stdin (only works with jpg images, but you can use convert to pipe to mencoder)<code>
mencoder \
  - \
  -demuxer lavf -lavfdopts format=mjpeg \
  <output options> \
  <output data>
</code>

  * Video filters:
    * ''-vf yadif=0'' : deinterlace
    * ''-vf scale=640:480'' : scale video
    * ''-vf crop=w:h:x:y'' : crop video
    * ''-vf "crop=640:360:0:60,scale=1280:720"'' : multiple video filters
    * ''-vf pp=?'' : post processing subfilters

=== Output data and options ===

Specify the video codec with ''-ovc'' option, and audio codec with ''-oac'' option. ''copy'' is possible with both.

  * **xvid** <code>
mencoder \
  <input data> \
  <input options> \
  -ovc xvid -xvidencopts bitrate=800:quant_type=mpeg:gmc:chroma_opt:vhq=4:bvhq=1:trellis \
  -o <output_file>
</code>xvid encode options:
    * ''bitrate=<value>'': constant bitrate, in kbs
    * ''fixed_quant=<1-31>'': constant quantization (quality), lower is better
    * ''trellis'' : speeds up encoding

  * **h264** <code>
mencoder \
  <input data> \
  <input options> \
  -ovc x264 -x264encopts bitrate=800 \
  -o <output_file>
</code>x264 encode options:
    * ''bitrate=<value>'': constant bitrate, in kbs
    * ''crf=<1.0-50.0>'': constant quality, lower is better

  * **WebM** <code>
mencoder \
  <input data> \
  <input options> \
  -ovc lavc -ffourcc VP80 -of lavf -lavfopts format=webm -lavcopts vcodec=libvpx:vqscale=22.0 \
  -o <output_file>
</code>lavc options:
    * ''vbitrate=<value>'': constant bitrate, in kbs
    * ''vqscale=<1.0-31.0>'': constant quantization (quality), lower is better

  * **mp3** <code>
mencoder \
  <input data> \
  <input options> \
  -oac mp3lame -lameopts abr:br=128 \
  -o <output_file>
</code>

=== Other operations ===

  * cut the file (here from 10'00" to 10'30"):<code>
mencoder -ss 10:00 -endpos 30 -ovc copy -oac copy movie.avi -o submovie.avi
</code>

==== ffmpeg ====

  * video codec: ''-c:v libx264'' or ''-c:v libxvid''
  * audio codec: ''-c:a pcm_s16le'' or ''libmp3lame'' for video codec
  * codec bitrate: video ''-b:v 800k'', audio ''-b:a 128k''
  * codec quality: video ''-q:v 20'', audio ''-q:a 90'', x264 ''-crf 20''

  * crop: ''-vf "crop=640:360:0:60"''
  * resize: ''-vf "scale=1280:720"''
  * pad: ''-vf "pad=1280:720:370:0"''
  * rotate: ''-vf "transpose=2"'' (0=CCW+VF, 1=CW, 2=CCW, 3=CW+VF)

  * blur: ''-vf boxblur=10:1''
  * overlay two videos:<code>
ffmpeg -i in1.avi -vf "movie=in2.avi [b]; [in][b] overlay=320:0"
</code><code>
ffmpeg -i in1.avi -i in2.avi -filter_complex "[0:v][1:v] overlay=320:0"
</code>

  * append side by side two videos:<code>
ffmpeg -i in_left.avi -vf "pad=1280:480 [left]; movie=in_right.avi [right]; [left][right] overlay=640:0" -c:v libx264 -b:v 800k out.avi
</code>

  * encode video from images sequence (eg for timelapse):<code>
ffmpeg -r 50 -i 01/all/image_1_%07d.pgm -c:v libx264 -b:v 800k video_01.avi
ffmpeg -r 10 -pattern_type glob -i "*.JPG" -c:v libsvtav1 -qp 20 video.mp4
</code>

  * cut clip (ss is start time, t is duration):<code>
ffmpeg -i in.avi -ss 00:00:23 -t 00:00:19 -vcodec copy -acodec copy out.avi
</code>

  * render subtitles (requires to be compiled with libass): ''-vf "subtitles=in.srt"''

  * transform portrait video 640x480 to landscape 1280x720 with blurry repeated sides:<code>
ffmpeg -i in.avi -filter_complex "[0:v] transpose=2,scale=1280:720,boxblur=10:1 [bg]; [0:v] transpose=2,scale=540:720 [fg]; [bg][fg] overlay=370:0 [out]" -map 
'[out]' -map 0:a -c:v libx264 -b:v 2000k -c:a copy out.avi
</code>
==== AviDemux ====

A GUI easier to use, like VirtualDub for Windows.


==== PhotoFilmStrip ====



==== Kdenlive ====

Tried Openshot and Cinelerra but seem crappy, Kdenlive seems to have better design.

  * Transitions : works between two video tracks that overlap (eg dissolve).
  * Audio track volume : add effect "Audio Correction / Volume (keyframable)", then double click to add modification points.
===== Audio =====

==== mp3 ====

=> ''lame''

To encode from wav to mp3 in "speech" quality :
<code bash>
lame -V2 --vbr-new -q0 --lowpass 10 -s 22.05 -b32 file.wav file.mp3
</code>

=> ''mp3cut''

To cut an mp3 file (warning: ID3 tags are not copied):
<code bash>
mp3cut -o output.mp3 -t 00:00:05+700-00:00:07+800 input.mp3
</code>

To concatenate mp3 files:
<code bash>
mp3cut -o output.mp3 input1.mp3 input2.mp3 input3.mp3
</code>

=> ''id3cp''

To copy ID3 tags from a file to another one.

=> ''id3v2''

To view and edit ID3 tags in command line.

=> ''kid3''

To view and edit ID3 tags in GUI.


==== ogg ====
(using vorbis-tools package)

=> ''oggenc''

To encode from wav to ogg in "speech" quality :
<code bash>
oggenc -b 32 --downmix --resample 22050 file.wav -o file.ogg
</code>

Converting from ogg to ogg in "speech" quality :
<code bash>
oggdec -b 16 -R file.ogg -o - | oggenc -r -B 16 -C 1 -b 32 --resample 22050 - -o file_recomp.ogg
</code>

==== sox ====
play, record, process

  * Cut: (start position / length)<code>
sox in_file.wav out_file.wav trim 2:37:32 4:00
</code>
  * Reencode:<code>
sox in_file.type1 out_file.type2
sox in_file.type1 -t type2 - | oggenc ...
</code>

==== ffmpeg ====

  * extract sound track from video: <code>
ffmpeg -i video.avi sound.mp3
</code>