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--- project:stereoscopy [2018/10/06 22:09] – dp
+++ project:stereoscopy [2018/10/17 10:20] (current) – dp
@@ Line 1: / Line 1: @@
 ====== Stereoscopic recording using FFmpeg ======
-FFmpeg is a free software project that produces libraries and programs for handling multimedia data. FFmpeg is available for under most operating systems (Windows, Linux, Mac OS X, Android...)
+This is I support material collected for Steroscopic/VR workshops by Radiona. We are using two identical USB cameras with FFmpeg for capturing video or images. FFmpeg is a free software project that produces libraries and programs for handling multimedia data available for most operating systems (Windows, Linux, Mac OS X, Android...)
 [[http://ffmpeg.org/]]
-<WRAP prewrap>
-<code>
-ffmpeg -help
-</code>
-</WRAP>
 ===== Accessing USB cameras =====
-Here we use two identical USB cameras for capturing. These examples are for Windows Windows os (DirectShow multimedia framework). Commands for accessing cameras on other operating sistem are here: [[https://trac.ffmpeg.org/wiki/Capture/Webcam]]. Linux/Debian ''v4l-utils'' package.
+Examples here are tested on Windows (DirectShow multimedia framework), but with small changes it should work on other systems. [[https://trac.ffmpeg.org/wiki/Capture/Webcam]]. Linux/Debian ''v4l-utils'' package.
-Example to list dshow input devices (Windows):
+List dshow input devices (Windows):
 <WRAP prewrap>
 <code>
@@ Line 21: / Line 15: @@
 </WRAP>
-Under Linux:
+Linux:
 <WRAP prewrap>
 <code>
@@ Line 28: / Line 22: @@
 </WRAP>
-Example to print a list of options from a selected device:
+Print a list of options from a selected device:
 <WRAP prewrap>
 <code>
@@ Line 43: / Line 37: @@
 ===== Camera calibration =====
-Preview obiju komara (za kalibraciju). Dva cam ulaza i overlay (checkerboard) za provjeru prekpapanja.
+Preview/overlay both cameras at the same time for position alignment (there is significant lag but still usable). Adjust for your camera name and supported formats & color modes.
 <WRAP prewrap>
 <code>
@@ Line 51: / Line 45: @@
 ===== Video recording =====
-Paralelno spremanje dvaju video inputa (kamere) u dva file-a. Svakako prije treba utvrditi koja je desna, a koja lijeva kamera.
+Parallel video recording of two cameras into separate files. Before recording find-out which one is ''right'' and ''left'' (Usually corresponds to order of plugging them).
 <WRAP prewrap>
 <code>
@@ Line 58: / Line 52: @@
 </WRAP>
-direktan stream, bez rekompresije (veća rezolucija i bez lag-a)
+Record direct ''mjpeg'' stream – bigger resolution and without lag.
 <WRAP prewrap>
 <code>
@@ Line 65: / Line 59: @@
 </WRAP>
-===== Framepacking =====
+===== Rotating the videos =====
-Pack two different video streams into a stereoscopic video, setting proper metadata on supported codecs. Convert left and right video to one side-by-side. [[https://ffmpeg.org/ffmpeg-filters.html#framepack]]
+In case you are recording with rotated cameras, we need to unrotate the video (in this case 90° CW).
+<WRAP prewrap>
+<code>
+ffmpeg -i LEFT.mp4 -codec:v libx264 -profile:v high -preset slower -b:v 1000k -vf "transpose=1" -threads 0 -codec:a aac -b:a 196k LEFT_rot.mp4
+</code>
+</WRAP>
+===== Framepacking in stereo video =====
+Pack two different video streams into a stereoscopic video, setting proper metadata on supported codecs. Convert left and right video to one side-by-side (''SBS''). [[https://ffmpeg.org/ffmpeg-filters.html#framepack]]
 <WRAP prewrap>
 <code>
@@ Line 80: / Line 82: @@
 </WRAP>
-Framepacking možda neće raditi sa falovima snimljenim s direktnim streamom, pa treba prije rekomprimirati forsirajući framerate.
+Convert views into a top-above-bottom format:
+<WRAP prewrap>
+<code>
+ffmpeg -i LEFT.mp4 -i RIGHT.mp4 -filter_complex framepack=tab OUTPUT_TAB.mp4
+</code>
+</WRAP>
+Framepacking might not work with files recorded with direct stream so we need to recompress it forcing the framerate.
 <WRAP prewrap>
 <code>
@@ Line 87: / Line 96: @@
 </code>
 </WRAP>
-===== Changing stereoscopic formats =====
+===== Metadata for Youtube video uploads =====
+Unfortunately none of the below recommended metadata work and Youtube is breaking things constantly. It might recognize stereoscopic/3D video in the computer browser (only anaglyph option) but it won't give the cardboard options on Youtube on smartphone. Additionally aspect ratio might be interpreted differently between computer and smartphone. It seems the best way for now is to prerender everything and bypass Youtube's unreliable/crappy 3d support. FIXME
+MPEG4 (with re-encoding):
+<WRAP prewrap>
+<code>
+ffmpeg -i input_file.mp4 -vcodec libx264 -x264opts frame-packing=3 output_file.mp4
+</code>
+</WRAP>
+<WRAP prewrap>
+<code>
+ffmpeg -i input_file.mkv -vcodec libx264 -x264opts "frame-packing=3:frame-packing-interpret=1:frame-packing-quincunx=0:frame-packing-grid=0,0,0,0" output_file.mp4
+</code>
+</WRAP>
+Matroska (direct stream copy)
+<WRAP prewrap>
+<code>
+ffmpeg -i input_file.mkv -c copy -metadata:s:v:0 stereo_mode=1 output_file.mkv
+</code>
+</WRAP>
+There is Google's tool for metadata injection but it also didn't work in this case.
+https://github.com/google/spatial-media/
+This fork is less strict and allows more operations: https://github.com/Vargol/spatial-media
+Add left-right (SBS) metadata:
+<WRAP prewrap>
+<code>
+python spatialmedia -i --stereo=left-right INPUT.mp4 OUTPUT.mp4
+</code>
+</WRAP>
+Print spatial media metadata contained in the file:
+<WRAP prewrap>
+<code>
+python spatialmedia FILE
+</code>
+</WRAP>
+===== Changing stereoscopic format =====
 Convert between different stereoscopic image formats.
 [[https://trac.ffmpeg.org/wiki/Stereoscopic]]
@@ Line 100: / Line 151: @@
 ===== Still image capture =====
-Direct stereo SBS image capture from usb cams. Postoji latencija između L i R slike ... FIXME
+Direct stereo SBS image capture from usb cams. There is lattency between ''left'' and ''rignt'' camera. FIXME
 <WRAP prewrap>
 <code>

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