videously

Videously is a bash script that relies on ffmpeg and sox to prepare videos for web delivery. It will normalize the audio within the video container as well as encode the video as an MP4, H.264 video ready for streaming in most browsers (see caniuse.com for details) and Flash.

videously uses the Main profile for H.264. This profile will run in most browsers, Flash Player, and iOS devices. Really old iOS devices require the baseline profile.

Dependencies

• ffmpeg. Make sure you install with H.264 (libx264) and AAC (libfaac) encoders
• sox. For normalizing the audio

Mac OS X / Homebrew users

Installing on Mac OS X for Homebrew users should be pretty easy:

$ brew install ffmpeg

$ brew install sox

It appears that the most recent brew recipe for ffmpeg now includes the needed x264 library for H.264 encoding.

Usage

$ ./videously.sh -i <video_file> -o <output_file>

Simply execute the script and give it a video to work from. Videosly is non-destructive to your original file. It will create the copies it needs and output a normalized web streaming file based on your given file. The <output_file> name is optional. If you supply it, videously will use that name for the file it creates. Without the <output_file> it simply prepends "web_normalized_" to the beginning of the file name used as input.

Audio Normalization Only

Passing a -a flag will normalize the audio within your video and create a new video with the existing video encoding and the new normalized audio. If you know that video will be processed later by another encoding system, this will allow you to get normalized audio, without multiple video encodings.

For example

./videously.sh -a -i source.mov

Making videously globaly available

I generally put tools like this in /usr/local/bin. When I do so, I typically drop the ".sh" from the name for a bash script like this. You can keep the file where you like. FWIW, it would move it like so:

$ mv videously.sh /usr/local/bin/videously

Doing so allows me to accesses it from any directory like:

$ videously -i <input_file> -o <output_file>

TODOS

1. Build progress indicator for H.264 encoding (it can take a while on large vids)
2. Put all temporarily generated files into a sub directory so as to not clutter the main directory.
3. Add feature wherein a directory of files could be processed

Tweaking / building your own

While videously works well for my workflow, your results may vary. The following are notes on how to interact with both ffmpeg and sox for use in tweaking or better understanding what videously is doing.

Normalize Audio for video files

Notes for creating a shell script to normalize sound in videos

Rip the audio into individual file:

$ ffmpeg -i <input> -c:a pcm_s16le -vn audio.wav

Rip the video into individual file:

$ ffmpeg -i <input> -map 0:1 -c:v copy -y silent.mov

Check available audio level multiplier

$ sox audio.wav -n stat -v

Bump up audio level

$ sox -v <audio_level_mult> audio.wav norm.wav

Merge files

$ ffmpeg -i silent.mov -i norm.wav -map 0:0 -map 1:0 -c:v copy -c:a libfaac normalized.mp4

Clean up temp files

$ rm audio.wav
$ rm norm.wav
$ rm silent.mov

Notes for ffmpeg, H.264 web encoding

The quick and dirty

ffmpeg -i <input_file> -c:v libx264 -preset slow -profile:v main -c:a copy -movflags +faststart output_file.mp4

What does that mean?

-i <input_file> -- Your input file

-c:v libx264 -- use the H.264 video codec

-preset slow -- slower the better. Options are ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow

-profile:v main -- Options are baseline, main, high. Older iOS only support baseline. I have found that main works for iPhone 4 and higher.

-c:a copy -- Use the existing audio codec. You can substitute this with libfaac to ensure that you are getting AAC audio. Generally you capture with that already.

As a side note libfaac has the following options:

• -ac -- number of audio channels
• -ar -- audio frequency rate in Hz (i.e. 44100, 48000, etc)
• -ab -- kilobits per second (i.e 192k, 128k, 96k, etc)

-movflags +faststart -- Moves MOOV atom to the beginning of the file

output_file.mp4 -- The name of your output file.

Other Options

Resizing

You can resize the video passing in the -s options with values such as "1024x640". This may require some digging however. At first glance it appears to want to be able to change size into something "divisable by 2". I was able to get it to work by only by cutting video in half, or doubling it. This seems related to needing to set a scale of sorts.

Links

Some helpful stuff at: http://rodrigopolo.com/ffmpeg/cheats.html