Generate video sample files suitable for Android Emulator testing

generate_samples.sh

#!/usr/bin/env bash

set -euo pipefail
IFS=$'\n\t'

# Audio generation

python3 - << EOF
import subprocess

sounds = [
    'Start playing',
    '30 seconds',
    '1 minute',
    '1 minute 30 seconds',
    '2 minutes',
    '2 minutes 30 seconds',
    '3 minutes',
    '3 minutes 30 seconds',
    '4 minutes',
    '4 minutes 30 seconds'
]

for v, i in enumerate(sounds):
    filename=f'sample_{v:02}_unpadded.aiff'
    out_filename=f'sample_{v:02}.wav'
    subprocess.run(['say', '-v', 'Ava', i, '-o', filename])
    subprocess.run(['ffmpeg', '-y', '-i', filename, '-filter','apad=whole_dur=30', out_filename])

EOF

sox sample*.wav out.wav
rm sample*wav

# Video generation
#
# -vprofile baseline to support playback in android emulator https://stackoverflow.com/questions/4910222/what-formats-of-video-will-play-in-emulator/13030509#13030509

ffmpeg -y -i out.wav -c:a aac -f lavfi -i testsrc2=duration=300:size=1280x720:rate=30 -vcodec libx264 -vprofile baseline -tune animation -crf 41 test_1280_16_9.mp4
ffmpeg -y -i out.wav -c:a aac -f lavfi -i testsrc2=duration=300:size=960x720:rate=30 -vcodec libx264 -vprofile baseline -tune animation -crf 41 test_960_3_4.mp4

ffmpeg -i [original_source.mp4] -i [overlay] -i [audio_source] -filter_complex \
"[0:v]scale=960:720[bg];[bg][1:v]overlay=0:0" -vcodec libx264 -vprofile baseline \
-tune animation -map 2:a:0 -t 00:3:10 -crf 41 -aspect 960:720 out_4_3.mp4