[FFmpeg-cvslog] r14711 - trunk/doc/ffmpeg-doc.texi

[stefano]

Author: stefano
Date: Tue Aug 12 12:07:28 2008
New Revision: 14711

Log:
Add to the ffmpeg docs an usage example showing how to extract images
from a video.


Modified:
   trunk/doc/ffmpeg-doc.texi

Modified: trunk/doc/ffmpeg-doc.texi
==============================================================================
--- trunk/doc/ffmpeg-doc.texi	(original)
+++ trunk/doc/ffmpeg-doc.texi	Tue Aug 12 12:07:28 2008
@@ -140,6 +140,25 @@ The mapping is particularly useful for D
 to get the desired audio language.
 
 NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
+
+* You can extract images from a video:
+
+ at example
+ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
+ at end example
+
+This will extract one video frame per second from the video and will
+output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
+etc. Images will be rescaled to fit the new WxH values.
+
+The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
+composed of three digits padded with zeroes to express the sequence
+number. It is the same syntax supported by the C printf function, but
+only formats accepting a normal integer are suitable.
+
+If you want to extract just a limited number of frames, you can use the
+above command in combination with the -vframes or -t option, or in
+combination with -ss to start extracting from a certain point in time.
 @c man end
 
 @chapter Invocation