mp4encode

MPEG-4编解码的实现(包括MPEG4视音频编解码)

#!/bin/sh
# mp4encode <avi-file>

# Initialize default values for options
convertRgb=0
videoWidth=320
videoHeight=240
fps=24
aspectRatio=1.33	# 4:3 standard definition TV aspect ratio
use_iso=0
vbitRate=500

use_mp3=0
abitRate=96

debug=0

# Process command line options
while getopts "A:IMRV:a:dh:r:w:" opt; do
	case $opt in
		A ) abitRate=$OPTARG ;;
		I ) use_iso=1 ;;
		M ) use_mp3=1 ;;
		R ) convertRgb=1 ;;
		V ) vbitRate=$OPTARG ;;
		a ) aspectRatio=$OPTARG ;;
		d ) debug=1 ;;
		h ) videoHeight=$OPTARG ;;
		r ) fps=$OPTARG ;;
		w ) videoWidth=$OPTARG ;;
		\? ) echo "usage: $0 [-w width] [-h height] [-r fps] [-a ratio] [-I] [-V kbps] [-M] [-A kbps] [-d] avifile [mp4file]"
			exit 1 ;;
	esac
done
shift `expr $OPTIND - 1`

if [ $debug = 1 ]; then
	set -x
fi

# The name of the AVI input file
avifile=$1
prefix=`expr $avifile : '\(.*\)\.avi'`

# The name of the MP4 output file
if [ -n "$2" ] ; then
	mp4file=$2
else
	mp4file=${prefix}.mp4
fi

# Check that the input AVI file exists
if [ ! -f "$avifile" ] ; then
	echo "Input file $avifile does not exist"
	exit 2
fi

# A few more initializations
rawframesize=`expr ${videoWidth} \* ${videoHeight} \* 3 / 2`
here=`pwd`

# For Divx encoder, this generates 1 I frame every two seconds
ifrequency=`expr $fps \* 2`

if [ $use_iso = 1 ]; then 
	# For ISO encoder, these default values 
	# yield I P B B P B B ... for every 1 second period
	bfrequency=2
	pfrequency=`expr \( $fps / \( $bfrequency + 1 \) \) - 1`
fi

# Create output directories for ISO video encoder if necessary
if [ $use_iso = 1 ]; then 
	if [ ! -d mp4vout ]; then
		mkdir mp4vout
	fi
	if [ ! -d yuvout ]; then
		mkdir yuvout
	fi
fi

date
echo "Starting encode of ${mp4file}"

if [ ! -f $prefix.yuv ] || [ $prefix.avi -nt $prefix.yuv ]; then
	echo "Extracting video from avi"
	tmpfile=./.tmp$$
	avi2raw -v $prefix.avi $prefix.yuv > $tmpfile

	# Convert from RGB24 to YUV12 if desired
	if [ $convertRgb = 1 ]; then
		mv $prefix.yuv $prefix.rgb
		echo "Converting video from RGB24 to YUV12"
		rgb2yuv -w $videoWidth -h $videoHeight $prefix.rgb $prefix.yuv
	fi

	# Perform simple check that we do indeed have raw YUV12 video
	numframes=`awk '{print $1}' $tmpfile`
	targetbytes=`expr ${numframes} \* ${rawframesize}`
	numbytes=`wc -c < ${prefix}.yuv`
	rm -f ${tmpfile}

	if [ $targetbytes != $numbytes ]; then
		echo "Extracted video isn't correct size for YUV12 ${videoWidth}x${videoHeight}"
		echo "Please check specified video frame size and YUV12 format"
		exit 2
	fi 

	# Crop video if desired
	if [ $aspectRatio != 1.33 ] ; then
		echo "Cropping video to ${aspectRatio}:1"
		lboxcrop -w ${videoWidth} -h ${videoHeight} -a ${aspectRatio} ${prefix}.yuv ${prefix}_crop.yuv
		mv ${prefix}_crop.yuv ${prefix}.yuv
	fi
fi

if [ $aspectRatio != 1.33 ] ; then
	videoHeight=`dc -e"$videoWidth $aspectRatio / p"`
	temp=`dc -e"$videoHeight 16 % p"`
	if [ $temp != 0 ] ; then
		videoHeight=`dc -e"16 $temp - $videoHeight + p"`
	fi
fi

numbytes=`wc -c < ${prefix}.yuv`
numframes=`expr ${numbytes} / ${rawframesize}`
lastframe=`expr ${numframes} - 1`

echo "Encoding ${numframes} frames of video"

if [ $use_iso = 0 ]; then 
	vfile=${prefix}.divx
	xvidenc -b ${vbitRate} -h ${videoHeight} -w ${videoWidth} -r ${fps} -i ${ifrequency} ${prefix}.yuv ${vfile}

else
	# Create video encoder parameters file from template
	isoBitRate=`expr ${vbitRate} \* 100000`
	sed -e "s?BASEDIR?${here}?" -e "s/FILEPREFIX/${prefix}/" -e "s/LASTFRAME/${lastframe}/" -e "s/FRAMEWIDTH/${videoWidth}/" -e "s/FRAMEHEIGHT/${videoHeight}/" -e "s/FRAMERATE/${fps}/" -e "s/BFREQUENCY/${bfrequency}/" -e "s/PFREQUENCY/${pfrequency}/" -e "s/BITRATE/${isoBitRate}/" /usr/local/share/mp4venc_template.par > ${prefix}.par 

	mp4venc ${prefix}.par
	vfile=${prefix}.cmp
	mv ./mp4vout/01/${vfile} ./${vfile}
	rm ./yuvout/01/${prefix}.yuv
fi

if [ $debug = 0 ]; then
	rm -f ${prefix}.yuv
fi

echo "Finished encoding video"

if [ ! -f $prefix.pcm ] || [ $prefix.avi -nt $prefix.pcm ]; then
	echo "Splitting out audio from avi"
	avi2raw -a ${prefix}.avi ${prefix}.pcm
fi

echo "Encoding audio"
if [ $use_mp3 = 0 ]; then 
	afile=${prefix}.aac
	faac -r -m4 -pLC -b${abitRate} ${prefix}.pcm ${afile}
else
	afile=${prefix}.mp3
	lame -r -x -h -b ${abitRate} ${prefix}.pcm ${afile}
fi

if [ $debug = 0 ]; then
	rm -f ${prefix}.pcm
fi

rm -f ${mp4file}

echo "Creating mp4 file with video"
mp4creator -c ${vfile} -rate=${fps} -H ${mp4file}

if [ $debug = 0 ]; then
	rm -f ${vfile}
fi

echo "Merging audio with video in mp4 file"
mp4creator -c ${afile} -H -O ${mp4file}

if [ $debug = 0 ]; then
	rm -f ${afile}
fi

if [ $debug = 1 ]; then
	set +o xtrace
fi

date
echo "Finished, results are in ${mp4file}"