Add options --video --refbpp, and compute average bitrate when no fixed bitrate is set.

1 files changed, 35 insertions, 9 deletions

diff --git a/localvideowebencode b/localvideowebencode
index d4670da..b225aac 100755
--- a/localvideowebencode
+++ b/localvideowebencode
@@ -31,6 +31,11 @@ Usage: $PRG [OPTION...] [--] [ARG=VALUE...] INPUTFILE... [ARG=VALUE...]
 Encode video file in multiple web-optimized formats, and provide sample
 html favoring open formats with optional non-JavaScript Flash fallback.
 
+    --video             Video style:
+                                       ref-bpp
+                          talkinghead    0.1
+                          action         0.15
+                        (default: none)
     -p, --profile       Video format - size with optional rate suffix,
                         delimited by @ (except for widescreen labels):
                         e.g. 848x480@25 480p25 wvga@25
@@ -51,8 +56,11 @@ html favoring open formats with optional non-JavaScript Flash fallback.
     -r, --rate          Video framerate - integer or fraction:
                         e.g. 15 1001/24000 25 1001/30000
                         (default: use input framerate)
-    -b, --bitrate       Video bitrate in bytes, with optional ISO suffix
-                        (default: none)
+    --refbpp            Reference bits-per-pixel (relative to 360p30),
+                        for computing average bitrate when not fixed.
+                        (default: 0.12)
+    -b, --bitrate       Fixed video bitrate in bytes: e.g. 768k 1M
+                        (default: none - use variable bitrate)
     --h264profile       MPEG-4 AVC target profile: baseline main high
                         (default: baseline)
     --h264preset        MPEG-4 AVC target preset: slow ultrafast etc.
@@ -81,15 +89,12 @@ Examples:
 Options before input files are passed to melt producer, and after to
 melt avformat consumer.
 
-When video bitrate is set, 2-pass encoding is used for MPEG-4 output.
-
 Hints:
   * Use square-pixel max. 480 width (vga 480p) for widest compatibility.
   * Use a modulus 16 profile (qvga vga 480p 720p) for best compression.
-  * Set bitrate for optimal MPEG-4/WebM bits-per-pixel ratio:
-    + talking head: 0.1
-    + high-motion or detailed content: 0.15
-    (inspect bits-per-pixel ratio with mediainfo)
+  * Try lower reference bits-per-pixel until visual quality is affected.
+  * Raise reference bits-per-pixel if needed, but no higher than 0.2.
+    (you can inspect actual bits-per-pixel and bitrate with mediainfo)
 
 More info:
 <http://camendesign.com/code/video_for_everybody>
@@ -110,7 +115,7 @@ exit1() {
 h264profile=baseline
 
 # parse cmdline options
-TEMP="`getopt -s sh -o hp:s:a:r:b:t: -l help,profile:,size:,aspect:,rate:,bitrate:,h264profile:,h264preset:,webmpreset:,audio:,stem:,title:,filter:,sample:: -n "$PRG" -- "$@"`" || exit1 "Internal getopt error."
+TEMP="`getopt -s sh -o hp:s:a:r:b:t: -l help,profile:,size:,aspect:,rate:,video:,refbpp:,bitrate:,h264profile:,h264preset:,webmpreset:,audio:,stem:,title:,filter:,sample:: -n "$PRG" -- "$@"`" || exit1 "Internal getopt error."
 eval set -- "$TEMP"
 while true ; do
 	case "$1" in
@@ -119,6 +124,8 @@ while true ; do
 	    -s|--size) size="$2"; shift 2;;
 	    -a|--aspect) aspect="$2"; shift 2;;
 	    -r|--rate) framerate="$2"; shift 2;;
+	    --video) video="$2"; shift 2;;
+	    --refbpp) refbpp="$2"; shift 2;;
 	    -b|--bitrate) bitrate_fixed="$2"; shift 2;;
 	    --h264profile) h264profile="$2"; shift 2;;
 	    --h264preset) h264preset="$2"; shift 2;;
@@ -241,6 +248,19 @@ done << EOF
 $(mediainfo --Inform="Video;%Width% %Height% %FrameRate%" "$infile_first")
 EOF
 
+case "$video" in
+    talkinghead)
+	refbpp="${refbpp:-0.1}"
+	;;
+    action)
+	refbpp="${refbpp:-0.15}"
+	;;
+    '')
+	refbpp="${refbpp:-0.12}"
+	;;
+    *) exit1 "Unknown video style \"$video\".";;
+esac
+
 case "$h264profile" in
     baseline|main)
 	_melt_h264="properties=x264-medium-$h264profile ${h264preset:+-vpre=libx264-$h264preset}"
@@ -264,6 +284,12 @@ if [ -n "$_pixels" ] && [ $_pixels -ge $((1024*768)) ]; then
 fi
 
 bitrate="$bitrate_fixed"
+# compute average bitrate from reference bits-per-pixel and "power of .75"
+if [ -n "$_pixels" ] && [ -n "$_frames" ]; then
+	bitrate="${bitrate_fixed:-$(perl \
+		-E "say int( +(($_pixels/(640*360))**0.75" \
+		-E "*640*360*$_frames*${refbpp:-$refbpp_default}) )")}"
+fi
 
 # default per-codec-channel bitrates
 bitrate_vorbis=64