Enhancement: Use Facebook video live stream in chat instead of text messages

[dumblob]

It seems Facebook recently introduced video live stream capability in chat. That means, we should definitely switch to it as it's prepared for low latency, high throughput, avoids potential account blocking due to unusually high message traffic, and it allows way easier stenography in case the sent data should be confident.

[gardner]

From the Facebook documentation: https://developers.facebook.com/docs/videos/live-video/getting-started#creating

Video Format:

• We accept video in maximum 720p (1280 x 720) resolution at 30 frames per second, with 1 key frame every 2 seconds
• You must send an I-frame (keyframe) at least once every two seconds throughout the stream.
• Recommended max bit rate is 4 mbps.
• Titles must be less than 255 characters otherwise the stream will fail
• The Live API accepts H264 encoded video and AAC encoded audio only

Video Length:

• 4 hour maximum length for live stream.
• 4 hour maximum length for preview streams (either through Live dialog or publisher tools). After 240 minutes, a new stream key must be generated.

Advanced Settings:

• Pixel Aspect Ratio: Square
• Frame Types: Progressive Scan
• Audio Sample Rate: 44.1 KHz
• Audio Bitrate: 128 Kbps mono
• Bitrate Encoding: CBR

[gardner]

Lossless encoding using YUV in h264: https://stackoverflow.com/questions/6701805/h264-lossless-coding/18506577#18506577

An audio modem library written in go: https://github.com/wiless/gocomm