Convert video to small size

convert-to-_-mp4.sh

#!/bin/sh
# Usage: convert-to-_-mp4.sh 320 28 $1
 
#SIZE=480
#QUAL=28
#NAME=MOVA0023.avi

SIZE=$1
QUAL=$2 # 18..28  18-best 28-small
NAME=$3

xterm -e \
ffmpeg \
    -i "$NAME" \
    -vf yadif,format=yuv420p \
    -vf scale=-1:$SIZE:force_original_aspect_ratio=decrease:force_divisible_by=2 \
    -force_key_frames "expr:gte(t,n_forced/2)" \
    -c:v libx264 \
    -crf $QUAL \
    -bf 2 \
    -c:a aac \
    -q:a 1 \
    -ac 2 \
    -ar 48000 \
    -use_editlist 0 \
    -movflags +faststart \
    "$NAME.$QUAL-$SIZE.mp4"

#     -crf 18 \
#     -b:v 512k \


# -vf specifies video filters
# yadif will deinterlace videos if they're interlaced.
# format=yuv420p will produce pixel format with 4:2:0 chroma subsampling.
# -force_key_frames "expr:gte(t,n_forced/2)" will place keyframes every half-second, so that will be the GOP size.
# -c:v libx264 will use the x264 encoder to produce a H264 video stream.
# -crf 18 will produce a visually lossless file. Better than setting a bitrate manually.
# -bf 2 will limit consecutive B-frames to 2
# -c:a aac will use the native encoder to produce an AAC audio stream.
# -q:a 1 sets the highest quality for the audio. Better than setting a bitrate manually.
# -ac 2 rematrixes audio to stereo.
# -ar 48000 resamples audio to 48000 Hz.
# -use_editlist 0 avoids writing edit lists.
# -movflags +faststart places moov atom/box at front of the output file.