TeslaCam-Merge-Videos (for AWS Lambda)

lambda_function.py

'''
    Function: TeslaCam-Merge-Videos
    Runtime:  Python 3.7
    Environment: AWS Lambda
    
    Description:
     This function is meant to be invoked by another Lambda (TeslaCam-Identify-Sets-and-Kickoff).
     Upon execution, it will use the 'event' key of the event dictionary (passed at runtime), and:
      
      1. Download camera angle video files from S3
      2. Use ffmpeg to determine clip duration
      3. Use ffmpeg to create a "fullscreen" video clip in the format
          [ camera-1 ][ camera-2 ][ camera-3 ] ... camera order determined by ENV variable
      
    ** Major credit to: https://github.com/ehendrix23/tesla_dashcam **
      -- This is simply one instantiation of the many possibilities offered by the above
     
    Environment Variables:
     - S3_BUCKET = the.name.of.your.bucket
     - CAMERA_NAMES = left_repeater, front, right_repeater (or as desired)
     - FFMPEG = /path/to/ffmpeg (e.g., /opt/ffmpeg-git-20190514-amd64-static/ffmpeg )
     - OUTPUT_FILEPATH = /tmp/output.mp4 (recommended)
    
    Assumptions:
     1. You have a Lambda Layer connected to the Lambda with ffmpeg library, etc.
     2. This Lambda function has a permissions Role enabling it to:
         a. Read from and Write to S3
         b. (Recommended) Write to CloudWatch Logs

'''

import boto3
import json
import subprocess
import os
from re import search

s3 = boto3.resource('s3')

def lambda_handler(event, context):

	inputs = []
	for camera_name in os.environ['CAMERA_NAMES'].split(","):
		camera_name = camera_name.strip()
		filename = "{}{}.mp4".format(event["event"], camera_name)
		local_filename = '/tmp/{}.mp4'.format(camera_name)
		
		# Get the video files from S3
		s3.meta.client.download_file(
			os.environ['S3_BUCKET'], 
			filename, 
			local_filename
		)
		
		inputs += ['-i', local_filename]
	
	# Use the last file to determine the appropriate duration
	command_result = subprocess.run([
		os.environ['FFMPEG'], 
		'-i', 
		local_filename, 
		'-hide_banner'],
		capture_output=True,
		text=True
	)
		
	for line in command_result.stderr.splitlines():
	    if search("^ *Duration: ", line) is not None:
		    line_split = line.split(',')
		    line_split = line_split[0].split(':', 1)
		    duration_list = line_split[1].split(':')
		    duration = int(duration_list[0]) * 60 * 60 + \
			    int(duration_list[1]) * 60 + \
			    int(duration_list[2].split('.')[0]) + \
			    (float(duration_list[2].split('.')[1]) / 100)
	
	# Build the ffmpeg filter argument
	#  Note: this will need revision if TeslaCam outputs more camera feeds
	ffmpeg_filter = 'color=duration={}:s=1920x480:c=black [base];'.format(duration) + \
		'[0:v] setpts=PTS-STARTPTS, scale=640x480, hflip [left];' + \
		'[1:v] setpts=PTS-STARTPTS, scale=640x480 [front];' + \
		'[2:v] setpts=PTS-STARTPTS, scale=640x480, hflip [right];' + \
		'[base][left] overlay=eof_action=pass:repeatlast=0:x=0:y=0 [left1];' \
		'[left1][front] overlay=eof_action=pass:repeatlast=0:x=640:y=0 [front1];' \
		'[front1][right] overlay=eof_action=pass:repeatlast=0:x=1280:y=0'

	# Build the final ffmpeg command
	ffmpeg_command = [os.environ['FFMPEG'],] + inputs + \
		['-filter_complex', ffmpeg_filter] + \
		['-preset', 'medium', '-crf', '28'] + \
		['-y', os.environ['OUTPUT_FILEPATH']]

	# Execute ffmpeg
	try:
		subprocess.run(ffmpeg_command)
	except subprocess.CalledProcessError as e:
		print(e.output)
		return { 'statusCode': 500, 'body': json.dumps('Poop.') }
	
	# Upload the result to the S3 with the fullscreen/ prefix
	s3.meta.client.upload_file(
		os.environ['OUTPUT_FILEPATH'], 
		os.environ['S3_BUCKET'], 
		"fullscreen/{}.mp4".format(event["event"].split("/")[1][:-1]),
		ExtraArgs={ 'ContentType': 'video/mp4', 'ACL':'public-read' }
	)
	
	return { 'statusCode': 200, 'body': json.dumps('It worked!') }