Convert videos to proper formats for HTML5 video on Linux shell using ffmpeg. Will probably convert this to a bash script later, but for the time being, here's some examples. Not sure there have actually sensible dimensions and bitrates for web video.

ffmpeg-html5

#!/usr/bin/env bash

FULLFILE="$1"
FILENAME=$(basename "$FULLFILE" | cut -d. -f1)

# webm
for size in 640x360; do
    ffmpeg -i $FULLFILE -f webm -vcodec libvpx -acodec libvorbis -ab 128000 -crf 22 -s ${size} ${FILENAME}-${size}.webm
done

# mp4
for size in 480x270 640x360 960x540 1280x720; do
	# ffmpeg -i $FULLFILE -acodec aac -strict experimental -ac 2 -ab 128k -vcodec libx264 -preset slow -f mp4 -crf 22 -s ${size} ${FILENAME}-${size}.mp4
    ffmpeg -i $FULLFILE -vcodec libx264 -f mp4 -vb 1024k -preset slow -pix_fmt yuv420p -s ${size} ${FILENAME}-${size}.mp4
done


# ogg (if you want to support older Firefox)
ffmpeg2theora ${FILENAME}-1280x720.mp4 -x 640 -y 360 --videoquality 5 --audioquality 5  --output ${FILENAME}-640x360.ogv

ffmpeg-html5.bat

REM mp4  (H.264 / ACC)
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -f mp4 -vcodec libx264 -acodec aac -ac 2 -ab 128k -vb 1024k -preset slow -crf 22 -s 640x360 "\\%~p1%~n1-640x360.mp4"
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -f mp4 -vcodec libx264 -acodec aac -ac 2 -ab 128k -vb 1024k -preset slow -crf 22 -s 1280x720 "\\%~p1%~n1-1280x720.mp4"
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -f mp4 -vcodec libx264 -acodec aac -ac 2 -ab 128k -vb 1024k -preset slow -crf 22 -s 960x540 "\\%~p1%~n1-960x540.mp4"
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -f mp4 -vcodec libx264 -acodec aac -ac 2 -ab 128k -vb 1024k -preset slow -crf 22 -s 480x270 "\\%~p1%~n1-480x270.mp4"
REM webm (VP8 / Vorbis)
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -f webm -b 1500k -vcodec libvpx -acodec libvorbis -ab 128000 -crf 22 -g 30 -s 640x360 "\\%~p1%~n1-640x360.webm"
REM ogv  (Theora / Vorbis)
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i %1 -b 1500k -vcodec libtheora -acodec libvorbis -ab 160000 -g 30 -s 640x360 "\\%~p1%~n1-640x360.ogv"
REM jpegs (screenshot every 24 frames)
"c:\program files\ffmpeg\bin\ffmpeg.exe" -i "%1" -r 1 -qscale:v 2 "\\%~p1%~n1.%%02d.jpg"

updated for better compatibility with QuickTime player by adding -pix_fmt yuv420p

added windows batch script