OvenMediaEngine has a built-in live transcoder. The live transcoder can decode the incoming live source and re-encode it with the set codec or adjust the quality to encode at multiple bitrates.
OvenMediaEngine currently supports the following codecs:
You can re-encode the incoming video source through the <Encode>
setting and make the encoded video and audio into a new stream. The newly created stream can be used according to the streaming URL format.
By the above setting, Video and Audio encoded with <Encode><Name>
of FHD and HD are newly created and included in <Stream><Name>
named ${OriginStreamName}_o
. In other words, if a stream inputted as app/stream
is transcoded, <Stream><Name>
named stream_o
is created.
Also, the newly created stream is used in the following URL format:
WebRTC
ws://192.168.0.1:3333/app/stream_o
HLS
http://192.168.0.1:8080/app/stream_o
/playlist.m3u8
MPEG-DASH
http://192.168.0.1:8080/app/stream_o
/manifest.mpd
Low-Latency MPEG-DASH
http://192.168.0.1:8080/app/stream_o
/manifest_ll.mpd
You can set the video profile as below:
The meaning of each property is as follows:
You can set the audio profile as below:
The meaning of each property is as follows:
You can configure Video and Audio to bypass transcoding as follows:
You need to consider codec compatibility with some browsers. For example, chrome only supports OPUS codec for audio to play WebRTC stream. If you set to bypass incoming audio, it can't play on chrome.
WebRTC doesn't support AAC, so if video bypasses transcoding, audio must be encoded in OPUS.
Even if you set up multiple codecs, there is a codec that matches each streaming protocol supported by OME, so it can automatically select and stream codecs that match the protocol. However, if you don't set a codec that matches the streaming protocol you want to use, it won't be streamed.
The following is a list of codecs that match each streaming protocol:
Therefore, you set it up as shown in the table. If you want to stream using HLS or MPEG-DASH, you need to set up H.264 and AAC, and if you want to stream using WebRTC, you need to set up Opus.
Also, if you are going to use WebRTC on all platforms, you need to configure both VP8 and H.264. This is because different codecs are supported for each browser, for example, VP8 only, H264 only, or both.
However, don't worry. If you set the codecs correctly, OME automatically sends the stream of codecs requested by the browser.
Currently, OME doesn't support adaptive streaming on HLS, MPEG-DASH. However, it will be updated soon.
Video Decoding
Audio Decoding
Video Encoding
Audio Encoding
H.264 (Baseline)
AAC
H.264 (Baseline)
AAC
VP8
Opus
Property
Description
Codec
Specifies the vp8
or h.264
codec to use
Width
Width of resolution
Height
Height of resolution
Bitrate
Bit per second
Framerate
Frames per second
Property
Description
Codec
Specifies the opus
or aac
codec to use
Bitrates
Bits per second
Samplerate
Samples per second
Channel
The number of audio channels
Protocol
Supported Codec
WebRTC
VP8, H.264, Opus
HLS
H.264, AAC
Low-Latency MPEG-Dash
H.264, AAC