webm.sh

#!/bin/bash

# /dbt/'s super awesome webm conversion script for bash v.1.0
#
# Just call $ bash ./webm.sh <source file>, supply basic info and boom, you get
# the converted webm in the subfolder ./webm!
# Alternatively, copy this to any directory in your PATH, make it executable
# and just call it by its name.
# See bottom of file for example terminal session.
#
# Limited choices for faster work.
# Resolution can be chosen freely out of three options (1280x720, 960x540 and
# 640x360) because it depends on source file frame rate.
# File size limits were chosen with some safety margin in mind; you can edit
# them if you want however (lines 52 and 56 -> maxsize).
#
# Choosing resolution:
# Start at 960x540. Convert. Does your webm look like shit or stutter? Go DOWN
# to 640x360, bitrate might be too low for this resolution. Is your webm way
# below the size limit? Go up to 1280x720.
# Rule of thumb for 30 fps video:
# up to 10 seconds -> 720p
# up to 30 seconds -> 540p
# over 30 seconds -> 360p
# If your webm is really long and exceeds the size limit, lower the resolution.
# A certain minimum bitrate is required so you likely won't be able to keep a
# 30 second 720p webm under 3 MB.

# get user input && calculate secondary params
echo "output file name"
read output
echo "start time (hh:mm:ss.t)"
read start
echo "duration (seconds[.decimals])"
read duration
echo "y-resolution {720, 540, 360}"
read v_res
if [ "$v_res" = "720" ]; then
    h_res="1280"
elif [ "$v_res" = "540" ]; then
    h_res="960"
elif [ "$v_res" = "360" ]; then
    h_res="640"
else
    echo "invalid resolution"
    exit
fi
echo "audio? [y|N]"
read audio
if [ "$audio" = "y" ]; then
    audiocmd="-c:a libvorbis -b:a 192K -vbr on"
    maxsize=3800
else
    audio="N"
    audiocmd="-an"
    maxsize=3000
fi
bitrate=$(echo "(8*$maxsize/$duration)" | bc)

# write user params into logfile
echo "converting $1:" >> ./webm_log.txt
echo "-----------------------" >> ./webm_log.txt
echo "start:       $start" >> ./webm_log.txt
echo "duration:    $duration s" >> ./webm_log.txt
echo "max bitrate: $bitrate kbps" >> ./webm_log.txt
echo "output file: ./webm/$output.webm" >> ./webm_log.txt
echo "resolution:  $h_res x $v_res" >> ./webm_log.txt
echo "audio:       $audiocmd" >> ./webm_log.txt
echo "" >> ./webm_log.txt

# write user params into stdout
echo
echo "converting $1:"
echo "-----------------------"
echo "start:       $start"
echo "duration:    $duration s"
echo "max bitrate: $bitrate kbps"
echo "output file: ./webm/$output.webm"
echo "resolution:  $h_res x $v_res"
echo "audio:       $audiocmd"
echo
echo "Press [Enter] to start converting!"
read confirm

# first pass
echo "ffmpeg -hide_banner -loglevel \"info\" -y -ss \"$start\" -t \"$duration\" -i \"$1\" -c:v libvpx -pass 1 -qmin 0 -qmax 50 -crf 10 -b:v 1M -threads 3 -speed 4 -g 128 -an -sn -f webm \"/dev/null\""
ffmpeg -hide_banner -loglevel "info" -y -ss "$start" -t "$duration" -i "$1" -c:v libvpx -pass 1 -qmin 0 -qmax 50 -crf 10 -b:v 1M -threads 3 -speed 4 -g 128 -an -sn -f webm "/dev/null"

# second pass
mkdir "./webm"
echo "ffmpeg -hide_banner -loglevel \"info\" -ss \"$start\" -t \"$duration\" -i \"$1\" -c:v libvpx -pass 2 -qmin 0 -qmax 50 -crf 10 -b:v \"$bitrate\" -s \"$h_res:$v_res\" $audiocmd -threads 3 -speed 0 -auto-alt-ref 1 -lag-in-frames 25 -g 128 -sn -f webm \"./webm/$output.webm\""
ffmpeg -hide_banner -loglevel "info" -ss "$start" -t "$duration" -i "$1" -c:v libvpx -pass 2 -qmin 0 -qmax 50 -crf 10 -b:v "$bitrate"k -s "$h_res:$v_res" $audiocmd -threads 3 -speed 0 -auto-alt-ref 1 -lag-in-frames 25 -g 128 -sn -f webm "./webm/$output.webm"

# cleanup
rm ffmpeg2pass-0.log

# Example terminal session, assuming this file and the video source are stored
# in ~/Videos:
#
#kkb@xubuntu:~$ cd Videos && ll
#total 1770580
#drwxr-xr-x  3 kkb kkb       4096 Sep 16 19:21 ./
#drwx------ 33 kkb kkb      12288 Sep 16 18:33 ../
#-rw-rw-r--  1 kkb kkb 1148006607 Aug  5  2015 Steel Panther 2015 08 03 West Hollywood, CA, USA   House of Blues Webcast 720p-GNNedc13ENs.webm
#-rw-rw-r--  1 kkb kkb  664883790 Jun 12 23:34 Steel Panther - Live from Lexxi’s Mom’s Garage DVD (Full Concert)-FXXcvntSlmY.mkv
#drwxrwxr-x  3 kkb kkb      28672 Sep 16 19:21 webm/
#-rw-rw-r--  1 kkb kkb      64366 Sep 10 22:26 webm.png
#-rw-rw-r--  1 kkb kkb       3612 Sep 16 18:31 webm.sh
#-rw-------  1 kkb kkb      11284 Sep 15 23:29 webm.txt
#kkb@xubuntu:~/Videos$ bash ./webm.sh "Steel Panther - Live from Lexxi’s Mom’s Garage DVD (Full Concert)-FXXcvntSlmY.mkv"
#output file name
#steel_panther
#start time (hh:mm:ss.t)
#00:10:10
#duration (seconds[.decimals])
#10
#y-resolution {720, 540, 360}
#720
#audio? [y|N]
#y
#
#converting Steel Panther - Live from Lexxi’s Mom’s Garage DVD (Full Concert)-FXXcvntSlmY.mkv:
#-----------------------
#start:       00:10:10
#duration:    10 s
#max bitrate: 3040 kbps
#output file: ./webm/steel_panther.webm
#resolution:  1280 x 720
#audio:       -c:a libvorbis -b:a 192K -vbr on
#
#Press [Enter] to start converting!
#
#ffmpeg -hide_banner -loglevel "info" -y -ss "00:10:10" -t "10" -i "Steel Panther - Live from Lexxi’s Mom’s Garage DVD (Full Concert)-FXXcvntSlmY.mkv" -c:v libvpx -pass 1 -qmin 0 -qmax 50 -crf 10 -b:v 1M -threads 3 -speed 4 -g 128 -an -sn -f webm "/dev/null"
# <ffmpeg output>
#mkdir: cannot create directory ‘./webm’: File exists
#ffmpeg -hide_banner -loglevel "info" -ss "00:10:10" -t "10" -i "Steel Panther - Live from Lexxi’s Mom’s Garage DVD (Full Concert)-FXXcvntSlmY.mkv" -c:v libvpx -pass 2 -qmin 0 -qmax 50 -crf 10 -b:v "3040" -s "1280:720" -c:a libvorbis -b:a 192K -vbr on -threads 3 -speed 0 -auto-alt-ref 1 -lag-in-frames 25 -g 128 -sn -f webm "./webm/steel_panther.webm"
# <ffmpeg output>
#kkb@xubuntu:~/Videos$ mpv ./webm/steel_panther.webm
# <mpv output>
#kkb@xubuntu:~/Videos$ exit