Set video bitrate (not generic bitrate), and leave unset by default (even if melt currently applies 200k limit internally). Unset audio sample rate and channel count by default. Use two-pass encoding only when bitrate explicitly set.

1 files changed, 15 insertions, 11 deletions

diff --git a/localvideowebencode b/localvideowebencode
index b89e6b0..7634525 100755
--- a/localvideowebencode
+++ b/localvideowebencode
@@ -27,8 +27,8 @@ html favoring open formats with optional non-JavaScript Flash fallback.
                         (default: use input size)
     -a, --aspect        Display Aspect Ratio in melt format e.g. @16/9
                         (default: no aspect hinting)
-    -b, --bitrate       Bitrate in bytes, optionally ISO appreviated
-                        (default: 768k)
+    -b, --bitrate       Video bitrate in bytes, with optional ISO suffix
+                        (default: none)
     -p, --profile       Video format (melt): square_ntsc qcif_15 etc.
                         (default: none - reuse input format)
     --h264profile       MPEG-4 AVC target profile (baseline medium)
@@ -49,11 +49,16 @@ Examples:
 Options before input files are passed to melt producer, and after to
 melt avformat consumer.
 
-Defaults are optimized for 320x240 (qvga).  For better quality use this:
+When video bitrate is set, 2-pass encoding is used for MPEG-4 output.
 
-    size:               640x480 (use lower numbers for widescreen!)
-    bitrate:            1120k
-    h264profile:        baseline
+Hints:
+  * Use max. 640x480 pixel size for widest compatibility
+    (ie. square-pixel 640x360 or anamorphic svcd_ntsc_wide for 16:9)
+  * Append these for single-mic speech: ac=1 ar=32000 ab=64k
+  * Set bitrate for optimal MPEG-4/WebM bits-per-pixel ratio:
+    + talking head: 0.1
+    + high-motion or detailed content: 0.15
+    (inspect result with mediainfo)
 
 More info:  <http://camendesign.com/code/video_for_everybody>
             <http://www.streaminglearningcenter.com/>
@@ -68,7 +73,6 @@ exit1() {
 }
 
 # defaults
-bitrate=768k
 h264profile=baseline
 
 # parse cmdline options
@@ -129,15 +133,15 @@ title=${title:-$stem}
 
 # TODO: When verified beneficial, add option real_time=-2
 args_in="-progress $sample ${profile:+-profile $profile}${args_in:+ $args_in}"
-args=" ${bitrate:+b=${bitrate}} ${size:+s=$size} ${aspect:+aspect=$aspect}"
-args_audio="ac=2 ar=44100 ab=96k"
+args=" ${bitrate:+vb=${bitrate}} ${size:+s=$size} ${aspect:+aspect=$aspect}"
+args_audio="ab=96k"
 
 ## Theora/Vorbis/Ogg
 melt -group $args_in $infiles -group $filters -consumer avformat:"$stem.ogg" f=ogg vcodec=libtheora $args acodec=libvorbis $args_audio $args_out
 
 ## H.264/AAC/MP4
-melt -group $args_in $infiles -group $filters -consumer avformat:/dev/null properties=x264-medium-pass1 properties=x264-medium-$h264profile $args $args_out
-melt -group $args_in $infiles -group $filters -consumer avformat:"$stem.mp4" pass=2 properties=x264-medium-$h264profile $args acodec=aac $args_audio $args_out
+[ -z "$bitrate" ] || melt -group $args_in $infiles -group $filters -consumer avformat:/dev/null properties=x264-medium-pass1 properties=x264-medium-$h264profile $args $args_out
+melt -group $args_in $infiles -group $filters -consumer avformat:"$stem.mp4" ${bitrate:+pass=2} properties=x264-medium-$h264profile $args acodec=aac $args_audio $args_out
 mv "$stem.mp4" "$stem.mp4"~
 qt-faststart "$stem.mp4"~ "$stem.mp4"
 [ -f "$stem.mp4" ] && rm "$stem.mp4"~ || exit1 "failed to optimize with qt-faststart."