Changes between Version 9 and Version 10 of Slideshow

Timestamp:

Aug 14, 2013, 11:21:16 PM (13 years ago)

Author:

llogan

Comment:

cleanup and expansion

Slideshow

@@ -1 @@
-This will create a video slideshow (using video codec libx264) from series of PNG images, named named img001.png, img002.png, img003.png, … 
+== Frame rates ==
 
-Here, each image will have a duration of 5 seconds (the inverse of 1/5 frames per second). By telling FFmpeg to set the input file's FPS option (frames per second) to some very low value, we made FFmpeg duplicate frames at the output and thus we achieved to display each image for some time on screen:
+This will create a video slideshow (using the encoder `libx264`) from series of numerically sequential PNG images named `img001.png`, `img002.png`, `img003.png`, etc.
+
+In this example each image will have a duration of 5 seconds (the inverse of 1/5 frames per second). By using a separate `-r` (frames per second) for the input and output you can control the duration at which each input is displayed and tell ffmpeg the frame rate you want for the output file. If the input `-r` is lower than the output `-r` ffmpeg will duplicate frames to reach your desired output frame rate. If the input `-r` is higher than the output `-r` ffmpeg will drop frames to reach your desired output frame rate.
+
+If you want the input and output frame rates to be the same, then just declare an input `-r` and the output will inherit the same value.
+
+Default for input is `-r 25` which will be used if no `-r` is used.
+
 {{{
-ffmpeg -f image2 -r 1/5 -i img%03d.png -c:v libx264 -r 30 out.mp4
+ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4
 }}}
 
 This will create a slideshow in which each image has a duration of 15 seconds:
+
 {{{
-ffmpeg -f image2 -r 1/15 -i img%03d.png -c:v libx264 -r 30 out.mp4
-}}}
-
-If you don't have images numbered and ordered in series (img001.jpg, img002.jpg, img003.jpg) but rather random bunch of images, ffmpeg also supports bash-style globbing (`*` represents any number of any characters):
-{{{
-ffmpeg -f image2 -r 1 -pattern_type glob -i '*.jpg' -c:v libx264 out.mp4
-}}}
-or for png images:
-{{{
-ffmpeg -f image2 -r 1 -pattern_type glob -i '*.png' -c:v libx264 out.mp4
+ffmpeg -r 1/15 -i img%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4
 }}}
 
 '''Important:''' All images in a series need to be of the same size and format.
 
-If you want to create a video out of just one image, this will do (output video duration is set to 30 seconds with `-t 30`):
+== Color space conversion and chroma sub-sampling ==
+
+By default when using `libx264`, and depending on your input, ffmpeg will attempt to avoid color subsampling. Technically this is preferred, but unfortunately almost all video players and many online video services only support YUV 4:2:0. PNG uses the RGB color space, so when using PNG images as your input you must add `-pix_fmt yuv420p` or `-vf format=yuv420p` if you want maximum compatibility. You can omit this if you are using JPG images as inputs.
+
+== Using a glob pattern ==
+
+ffmpeg also supports bash-style globbing (`*` represents any number of any characters). This is useful if your images are sequential but not necessarily in a numerically sequential order as in the previous examples.
+
 {{{
-ffmpeg -loop 1 -f image2 -i img.png -c:v libx264 -t 30 out.mp4
+ffmpeg -r 1 -pattern_type glob -i '*.jpg' -c:v libx264 out.mp4
 }}}
 
+For PNG images:
+
+{{{
+ffmpeg -r 1 -pattern_type glob -i '*.png' -c:v libx264 -pix_fmt yuv420p out.mp4
+}}}
+
+== Using a single image as an input ==
+
+If you want to create a video out of just one image, this will do (output video duration is set to 30 seconds with `-t 30`):
+
+{{{
+ffmpeg -loop 1 -i img.png -c:v libx264 -t 30 -pix_fmt yuv420p out.mp4
+}}}
+
+== Adding audio ==
+
 If you want to add audio (e.g. `audio.wav`) to one "poster" image, you need `-shortest` to tell it to stop after the audio stream is finished. We use the internal AAC encoder, but you can [[AACEncodingGuide|use any other AAC encoder]] as well:
+
 {{{
-ffmpeg -loop 1 -f image2 -i img.png -i audio.wav -c:v libx264 -c:a aac -strict experimental -b:a 192k -shortest out.mp4
+ffmpeg -loop 1 -i img.jpg -i audio.wav -c:v libx264 -c:a aac -strict experimental -b:a 192k -shortest out.mp4
 }}}
 
 
-'''See also:'''
-[[Create a thumbnail image every X seconds of the video]]
+== See also ==
+* [[Create a thumbnail image every X seconds of the video]]
+* [[x264EncodingGuide|x264 Encoding Guide]]