cloud engineer
If your audio is out of sync, you can fix using ffmpeg.
ffmpeg -i source.mp4 \ -i livestream.mp4 \ -map 0:0 -map 1:1 \ -acodec copy \ -vcodec copy \ -itsoffset 0.100 \ output.mp4 |
The ffmpeg fix is fast. A 1GB file took less than 30 seconds to run. Adjust -tsoffset until you find the sweet spot.
If you have a video with audio sync issues, you can easily fix it using ffmpeg. It takes 2 inputs: the filename and delay: 0.100 is 100 ms or 0.1 seconds. Output file has -fixed appended to it. It’s fast. Only takes 2-3 seconds to process a 1.5 hour recording.
Here’s the script.
ffmpeg -i livestream.mp4 \ -itsoffset 0.100 \ -i livestream.mp4 \ -map 0:0 -map 1:1 \ -acodec copy \ -vcodec copy \ livestream-fixed.mp4 |
How to convert MP3 to OGG audio format.
ffmpeg -i in.mp3 -ar 48000 -vn -c:a libvorbis out.ogg |
If you have sample rate errors, use -vn.
If you have video files that are formatted in MPEG-2, video files with a .m2ts extension, you can convert them to MP4 using ffmpeg.
ffmpeg -i input.ts -c:v libx264 -c:a aac output.mp4 |
The video is encoded using open format H.264, while audio is encoded using AAC.
This is a follow up to a previous post about FFMPEG. In addition to sending a RTMP stream, you can also set a start time and duration.
Here’s how to set the start time using -ss option and -to for the duration. Video will start at 1 min 23 secs and play until 2 mins.
ffmpeg -ss 00:01:23 -i video.mp4 -to 00:02:00 -c copy -copyts cut.mp4 |
Here’s how to start time to start the video at 1 min 23 sec for RTMP streaming. Please note, the start time option needs to be before the input file.
ffmpeg -ss 00:01:23 \ -re -i $1 -acodec libmp3lame -ar 44100 -b:a 128k \ -pix_fmt yuv420p -profile:v baseline -s 1280x720 -bufsize 6000k \ -vb 1200k -maxrate 1500k -deinterlace -vcodec libx264 \ -preset veryfast -g 30 -r 30 -f flv \ -flvflags no_duration_filesize \ "rtmp://username:password@yourserver:1935/live/backup" |
FFMPEG is the jack of all trades utility for both audio and video files. You can record, convert, and even live stream an audio or video file in just about any file format. In this example, I will be sending a RTMP stream of a MP4 file to a Wowza streaming server. I can easily send the same stream to YouTube, Facebook or any streaming server that accepts a RTMP source. In this example, I created simple Bash script called play.sh, with all the options needed to live stream to Wowza Streaming server.
Here are the options in play.sh.
ffmpeg -re -i $1 -acodec libmp3lame -ar 44100 -b:a 128k \ -pix_fmt yuv420p -profile:v baseline -s 1280x720 -bufsize 6000k \ -vb 1200k -maxrate 1500k -deinterlace -vcodec libx264 \ -preset veryfast -g 30 -r 30 -f flv \ -flvflags no_duration_filesize \ "rtmp://username:password@yourserver:1935/live/backup" |
To launch, run the script.
bash play.sh filename.mp4 |
Convert MP3 to Vorbis OGG format using ffmpeg.
ffmpeg -i input.mp3 -c:a libvorbis -q:a 4 output.ogg |
If you want multiple files, use a loop.
for f in ./*.mp3; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f/%mp3/ogg}"; done |
FFmpeg is a complete cross-platform command-line tool for recording, converting and streaming audio and video files. FFmpeg is widely used for converting files from one format to another. It also used by some to record videos from the screen or camera. It’s also used by others to live stream a recorded file or camera to a RTMP streaming server such as Wowza, YouTube or Facebook Live.
How to record your camera to a video file.
$ ffmpeg -f avfoundation -i "1:0" -t 00:00:15 -s 1280x720 -r 30 -b:v 3500k -b:a 128k out.mpg $ ffmpeg -f avfoundation -i "2:0" -t 00:00:15 -s 1280x720 -r 30 -b:v 3500k -b:a 128k out.mpg |
-i = “video:audio”
-t = duration
-r = fps
-b:v = video bitrate
-b:a = audio bitrate
How to stream a video file to a RTMP server
$ ffmpeg -re -i input.mp4 -vcodec libx264 -preset veryfast -maxrate 1500k -c:a aac -b:a 128k -ac 2 -ar 44100 -f flv rtmp://yourserver:1935/live/mystream |
How to live stream your screen monitor to a RTMP server
$ ffmpeg -f avfoundation -i "2:0" -vcodec libx264 -preset ultrafast -pix_fmt yuv420p -s 1280x720 -r 30 -b:v 1500k -bufsize 1500k -maxrate 7000k -c:a aac -b:a 128k -ac 2 -ar 44100 -f flv rtmp://yourserver:1935/live/mystream |
How to stream your camera to a RTMP server
$ ffmpeg -f avfoundation -i "1:0" -vcodec libx264 -preset ultrafast -pix_fmt yuv420p -s 1280x720 -r 30 -b:v 1500k -bufsize 1500k -maxrate 7000k -c:a aac -b:a 128k -ac 2 -ar 44100 -f flv rtmp://yourserver:1935/live/mystream |
To learn details of FFmpeg options, read the documentation.
If you need assistance with the install, please see my previous post.