Apple supports Low-Latency HLS (LLHLS), which enables low-latency video streaming while maintaining scalability. LLHLS enables broadcasting with an end-to-end latency of about 2 to 5 seconds. OvenMediaEngine officially supports LLHLS as of v0.14.0.

LLHLS is an extension of HLS, so legacy HLS players can play LLHLS streams. However, the legacy HLS player plays the stream without using the low-latency function.

Configuration

To use LLHLS, you need to add the <LLHLS> elements to the <Publishers> in the configuration as shown in the following example.

<Server version="8">
    <Bind>
        <Publishers>
            <LLHLS>
            <!-- 
        OME only supports h2, so LLHLS works over HTTP/1.1 on non-TLS ports. 
        LLHLS works with higher performance over HTTP/2, 
        so it is recommended to use a TLS port.
        -->
        <Port>80</Port>
        <TLSPort>443</TLSPort>
        <WorkerCount>1</WorkerCount>
        </LLHLS>
        </Publishers>
    </Bind>
    <VirtualHosts>
    <VirtualHost>
            <Applications>
                <Application>
                    <Publishers>
            <LLHLS>
                <ChunkDuration>0.2</ChunkDuration>
                <SegmentDuration>6</SegmentDuration>
                <SegmentCount>10</SegmentCount>
                <CrossDomains>
                    <Url>*</Url>
                </CrossDomains>
            </LLHLS>
                    </Publishers>
                </Application>
            </Applications>
        </VirtualHost>
    </VirtualHosts>
</Server>

Adaptive Bitrates Streaming (ABR)

LLHLS can deliver adaptive bitrate streaming. OME encodes the same source with multiple renditions and delivers it to the players. And LLHLS Player, including OvenPlayer, selects the best quality rendition according to its network environment. Of course, these players also provide option for users to manually select rendition.

See the Adaptive Bitrates Streaming section for how to configure renditions.

CrossDomain

Most browsers and players prohibit accessing other domain resources in the currently running domain. You can control this situation through Cross-Origin Resource Sharing (CORS) or Cross-Domain (CrossDomain). You can set CORS and Cross-Domain as <CrossDomains> element.

<CrossDomains>
    <Url>*</Url>
    <Url>*.airensoft.com</Url>
    <Url>http://*.ovenplayer.com</Url>
    <Url>https://demo.ovenplayer.com</Url>
</CrossDomains>

You can set it using the <Url> element as shown above, and you can use the following values:

Streaming

LLHLS is ready when a live source is inputted and a stream is created. Viewers can stream using OvenPlayer or other players.

If your input stream is already h.264/aac, you can use the input stream as is like below. If not, or if you want to change the encoding quality, you can do Transcoding.

<OutputProfiles>
    <OutputProfile>
        <Name>bypass_stream</Name>
        <OutputStreamName>${OriginStreamName}</OutputStreamName>
        <Encodes>
            <Audio>
                <Bypass>true</Bypass>
            </Audio>
            <Video>
                <Bypass>true</Bypass>
            </Video>
        </Encodes>
    </OutputProfile>
</OutputProfiles>

When you create a stream, as shown above, you can play LLHLS with the following URL:

http[s]://domain[:port]/<app name>/<stream name>/llhls.m3u8

If you use the default configuration, you can start streaming with the following URL:

https://domain:3334/app/<stream name>/llhls.m3u8

We have prepared a test player that you can quickly see if OvenMediaEngine is working. Please refer to the Test Player for more information.

Live Rewind

You can create as long a playlist as you want by setting <DVR> to the LLHLS publisher as shown below. This allows the player to rewind the live stream and play older segments. OvenMediaEngine stores and uses old segments in a file in <DVR><TempStoragePath> to prevent excessive memory usage. It stores as much as <DVR><MaxDuration> and the unit is seconds.

<LLHLS>
    ...
    <DVR>
        <Enable>true</Enable>
        <TempStoragePath>/tmp/ome_dvr/</TempStoragePath>
        <MaxDuration>3600</MaxDuration>
    </DVR>
    ...
</LLHLS>

ID3v2 Timed Metadata

ID3 Timed metadata can be sent to the LLHLS stream through the Send Event API.

Dump

You can dump the LLHLS stream for VoD. You can enable it by setting the following in <Application><Publishers><LLHLS>. Dump function can also be controlled by Dump API.

<LLHLS>
    <Dumps>
        <Dump>
            <Enable>true</Enable>
            <TargetStreamName>stream*</TargetStreamName>
            
            <Playlists>
                <Playlist>llhls.m3u8</Playlist>
                <Playlist>abr.m3u8</Playlist>
            </Playlists>
    
            <OutputPath>/service/www/ome-dev.airensoft.com/html/${VHostName}_${AppName}_${StreamName}/${YYYY}_${MM}_${DD}_${hh}_${mm}_${ss}</OutputPath>
        </Dump>
    </Dumps>
    ...
</LLHLS>

TargetStreamName

The name of the stream to dump to. You can use * and ? to filter stream names.

Playlists

The name of the master playlist file to be dumped together.

OutputPath

The folder to output to. In the OutputPath you can use the macros shown in the table below. You must have write permission on the specified folder.

DRM (beta)

OvenMediaEngine supports Widevine and Fairplay in LLHLS with simple setup since version 0.16.0.

To include DRM information in your LLHLS Publisher configuration, follow these steps. You can set the InfoFile path as either a relative path, starting from the directory where Server.xml is located, or as an absolute path.

<LLHLS>
    <ChunkDuration>0.5</ChunkDuration>
    <PartHoldBack>1.5</PartHoldBack>
    <SegmentDuration>6</SegmentDuration>
    <SegmentCount>10</SegmentCount>
    <DRM>
        <Enable>false</Enable>
        <InfoFile>path/to/file.xml</InfoFile>
    </DRM>
    <CrossDomains>
        <Url>*</Url>
    </CrossDomains>
</LLHLS>

The separation of the DRMInfoFile is designed to allow dynamic changes to the file. Any modifications to the DRMInfoFile will take effect when a new stream is generated.

Here's how you should structure your DRM Info File:

<?xml version="1.0" encoding="UTF-8"?>

<DRMInfo>
    <DRM>
        <Name>MultiDRM</Name>
        <VirtualHostName>default</VirtualHostName>
        <ApplicationName>app</ApplicationName>
        <StreamName>stream*</StreamName> <!-- Can be a wildcard regular expression -->
        <CencProtectScheme>cbcs</CencProtectScheme> <!-- Currently supports cbcs only -->
        <KeyId>572543f964e34dc68ba9ba9ef91d4xxx</KeyId> <!-- Hexadecimal -->
        <Key>16cf4232a86364b519e1982a27d90xxx</Key> <!-- Hexadecimal -->
        <Iv>572547f914e34dc68ba9ba9ef91d4xxx</Iv> <!-- Hexadecimal -->
        <Pssh>0000003f7073736800000000edef8ba979d64acea3c827dcd51d21ed0000001f1210572547f964e34dc68ba9ba9ef91d4c4a1a05657a64726d48f3c6899xxx</Pssh> <!-- Hexadecimal, for Widevine -->
        <!-- Add Pssh for FairPlay if needed -->
        <FairPlayKeyUrl>skd://fiarplay_key_url</FairPlayKeyUrl> <!-- FairPlay only -->
    </DRM>
    <DRM>
        <Name>MultiDRM2</Name>
        <VirtualHostName>default</VirtualHostName>
        <ApplicationName>app2</ApplicationName>
        <StreamName>stream*</StreamName> <!-- Can be a wildcard regular expression -->
         ...........
    </DRM>
</DRMInfo>

Multiple <DRM> can be set. Specify the VirtualHost, Application, and StreamName where DRM should be applied. StreamName supports wildcard regular expressions.

Currently, CencProtectScheme only supports "cbcs" since FairPlay also supports only cbcs. There may be limited prospects for adding other schemes in the near future.

KeyId, Key, Iv and Pssh values are essential and should be provided by your DRM provider. FairPlayKeyUrl is only need for FairPlay and if you want to enable FairPlay to your stream, it is required. It will be also provided by your DRM provider.

OvenPlayer now includes DRM-related options. Enable DRM and input the License URL. Your content is now securely protected.

Pallycon DRM

OvenMediaEngine integrates with Pallycon, allowing you to more easily apply DRM to LLHLS streams.

To integrate Pallycon, configure the DRMInfo.xml file as follows.

<?xml version="1.0" encoding="UTF-8"?>

<DRMInfo>
    <DRM>
        <Name>Pallycon</Name>
        <VirtualHostName>default</VirtualHostName>
        <ApplicationName>app</ApplicationName>
        <StreamName>stream*</StreamName> <!-- Can be wildcard regular expression -->

        <DRMProvider>Pallycon</DRMProvider> <!-- Manual(default), Pallycon -->
        <DRMSystem>Widevine,Fairplay</DRMSystem> <!-- Widevine, Fairplay -->
        <CencProtectScheme>cbcs</CencProtectScheme> <!-- cbcs -->
        <ContentId>${VHostName}_${AppName}_${StreamName}</ContentId>
        <KMSUrl>https://kms.pallycon.com/v2/cpix/pallycon/getKey/</KMSUrl>
        <KMSToken>xxxx</KMSToken>
    </DRM>
</DRMInfo>

Set DRMProviderto Pallycon. Then, set the necessary information as shown in the example. KMSUrl and KMSToken are values provided by the Pallycon console. ContentId can be created using VHostName, AppName, and StreamName macros.

OvenMediaEngine uses WebRTC to provide sub-second latency streaming. WebRTC uses RTP for media transmission and provides various extensions.

OvenMediaEngine provides the following features:

Configuration

If you want to use the WebRTC feature, you need to add <WebRTC> element to the <Publishers> and <Ports> in the Server.xml configuration file, as shown in the example below.

ICE

WebRTC uses ICE for connections and specifically NAT traversal. The web browser or player exchanges the Ice Candidate with each other in the Signalling phase. Therefore, OvenMediaEngine provides an ICE for WebRTC connectivity.

If you set IceCandidate to *: 10000-10005/udp, as in the example above, OvenMediaEngine automatically gets IP from the server and generates IceCandidate using UDP ports from 10000 to 10005. If you want to use a specific IP as IceCandidate, specify a specific IP. You can also use only one 10000 UDP Port, not a range, by setting it to *: 10000.

Signalling

OvenMediaEngine has embedded a WebSocket-based signalling server and provides our defined signalling protocol. Also, OvenPlayer supports our signalling protocol. WebRTC requires signalling to exchange Offer SDP and Answer SDP, but this part isn't standardized. If you want to use SDP, you need to create your exchange protocol yourself.

If you want to change the signaling port, change the value of <Ports><WebRTC><Signalling>.

Signalling Protocol

The Signalling protocol is defined in a simple way:

If you want to use a player other than OvenPlayer, you need to develop the signalling protocol as shown above and can integrate OvenMediaEngine.

Streaming

Publisher

Add WebRTC element to Publisher to provide streaming through WebRTC.

Encoding

WebRTC Streaming starts when a live source is inputted and a stream is created. Viewers can stream using OvenPlayer or players that have developed or applied the OvenMediaEngine Signalling protocol.

Also, the codecs supported by each browser are different, so you need to set the Transcoding profile according to the browser you want to support. For example, Safari for iOS supports H.264 but not VP8. If you want to support all browsers, please set up VP8, H.264, and Opus codecs in all transcoders.

WebRTC doesn't support AAC, so when trying to bypass transcoding RTMP input, audio must be encoded as opus. See the settings below.

Playback

If you created a stream as shown in the table above, you can play WebRTC on OvenPlayer via the following URL:

If you use the default configuration, you can stream to the following URL:

• ws://[OvenMediaEngine IP]:3333/app/stream

• wss://[OvenMediaEngine IP]:3333/app/stream

Adaptive Bitrates Streaming (ABR)

OvenMediaEnigne provides adaptive bitrates streaming over WebRTC. OvenPlayer can also play and display OvenMediaEngine's WebRTC ABR URL.

Create Playlist for WebRTC ABR

You can provide ABR by creating a playlist in <OutputProfile> as shown below. The URL to play the playlist is ws[s]://domain[:port]/<app name>/<stream name>/<playlist file name>

<Playlist><Rendition><Video> and <Playlist><Rendition><Audio> can connected using <Encodes><Video><Name> or <Encodes><Audio><Name>.

If <Options><WebRtcAutoAbr> is set to true, OvenMediaEngine will measure the bandwidth of the player session and automatically switch to the appropriate rendition.

Here is an example play URL for ABR in the playlist settings below. wss://domain:13334/app/stream/abr

Multiple codec support in Playlist

WebRTC can negotiate codecs with SDP to support more devices. Playlist can set rendition with different kinds of codec. And OvenMediaEngine includes only renditions corresponding to the negotiated codec in the playlist and provides it to the player.

In the example below, it consists of renditions with H.264 and Opus codecs set and renditions with VP8 and Opus codecs set. If the player selects VP8 in the answer SDP, OvenMediaEngine creates a playlist with only renditions containing VP8 and Opus and passes it to the player.

WebRTC over TCP

Turn on TURN server

You can turn on the TURN server by setting <TcpRelay> in the WebRTC Bind.

Example : <TcpRelay>*:3478</TcpRelay>

WebRTC over TCP with OvenPlayer

You can play the WebRTC stream over TCP by attaching the query transport=tcp to the existing WebRTC play URL as follows.

OvenPlayer automatically sets iceServers by obtaining TURN server information set in <TcpRelay> through signaling with OvenMediaEngine.

Custom player

If you are using custom player, set iceServers like this: