Created An Example on Live VP8 Transcoding + Packaging (markdown)

An-Example-on-Live-VP8-Transcoding---Packaging.md

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+
+This example uses pipe to chain transcoding and packaging together. Another option is to use socket.
+
+Assuming you have a live iptv stream available at `225.1.1.8:8001` at port `8001` with interface address `172.29.46.122`.
+
+## Create Pipe
+
+```
+mkfifo pipe1
+```
+
+## Transcoding Command
+
+```
+ffmpeg -i udp://225.1.1.8:8001?localaddr=172.29.46.122 -g 90 -speed 4 -threads 8 -c:v libvpx -f webm pipe: > pipe1
+```
+
+Option `-speed 4` tells the encoder to encode really fast, sacrificing quality. This is needed otherwise ffmpeg is not fast enough to keep up with the live stream.
+
+## Packaging Command
+
+```
+packager in=pipe1,stream=audio,init_segment=livehd-audio.webm,segment_template=livehd-audio-\$Number\$.webm in=pipe1,stream=video,init_segment=livehd-video.webm,template=livehd-video-\$Number\$.webm  --mpd_output livehd.mpd  --profile live --dump_stream_info --min_buffer_time=10 --time_shift_buffer_depth=300 --segment_duration=3 --io_block_size 65536
+```
+
+Option `-io_block_size 65536` tells packager to use an io_block_size of 65K for threaded io file. This is necessary as reading from pipe blocks until the specified number of bytes, which is specified in io_block_size for threaded io file, thus the value of io_block_size cannot be too large.
+
+This example cannot be easily extended to support more streams and add encryption.