Support for Steam Broadcasting

PolarManne commented 9 years ago

It just got introduced this morning, and it's be nice to see it implemented. http://steamcommunity.com/?subsection=broadcasts

TkTech commented 9 years ago

The stream is interesting. For now, it appears to require a logged in user to work. Examples are all for this live stream: http://steamcommunity.com/broadcast/watch/76561198067563695

First, a request is made to get the video stream. Example:

http://steamcommunity.com/broadcast/getbroadcastmpd/?steamid=76561198067563695&broadcastid=0

{
    "success": "ready",
    "retry": 0,
    "broadcastid": "12547374920780913142",
    "url": "http://81.171.106.194:80/broadcast/3118622223253298157/manifest/?viewer=87917971236267582",
    "appid": "570",
    "app_title": "Dota 2",
    "title": "Dota 2",
    "viewer_count": 194
}

Then you take the url value in the JSON returned to find the manifest. Example:

http://81.171.106.194/broadcast/3118622223253298157/manifest/?viewer=user_id

Where user_id is your steam community user id (looks like 76561198067563695). Result is as below:

<MPD xmlns="urn:mpeg:DASH:schema:MPD:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="dynamic" availabilityStartTime="2014-12-02T19:54:15Z" publishTime="2014-12-02T19:54:15Z" minimumUpdatePeriod="PT30S" minBufferTime="PT3S" timeShiftBufferDepth="PT120S">
<Period id="1" start="PT0S">
<AdaptationSet id="1" segmentAlignment="true" startWithSAP="1" maxWidth="1280" maxHeight="720" lang="und">
<ContentComponent id="1" contentType="video"/>
<ContentComponent id="2" contentType="audio"/>
<SegmentTemplate timescale="1000" duration="3000" media="http://broadcast.akamai.steamstatic.com/broadcast/3118622223253298157/segment/$Number$/?broadcast_origin=par_valve129" startNumber="1" initialization="http://broadcast.akamai.steamstatic.com/broadcast/3118622223253298157/segment/init/?broadcast_origin=par_valve129"/>
<Representation id="main" mimeType="video/mp4" codecs="avc1.4d4032,mp4a.40.2" sar="1:1" audioSamplingRate="48000" startWithSAP="1" bandwidth="3500"></Representation>
</AdaptationSet>
</Period>
</MPD>

These videos can be rewound, and appear to be in 3 second chunks (the duration field, divided by the timescale field). So for every 3 seconds, you make a request to

... to get the next/previous chunk of mp4 video.

Notes:

It looks like this has been setup to allow multiple streams per user, but currently m_ulBroadcastID is hardcoded to 0, so any url that has a broadcastid in it should just be 0.
All of the IDs used in the broadcast system are steam community ids (big long numbers like 76561198067563695) and not the older steamids.
There is only one codec supported, video/mp4;codecs="avc1.4d4032,mp4a.40.2

Kein commented 9 years ago

For some weird reason it always 3500000 for bandwidth. Regardless of what bitrate source/streamer chooses.

TkTech commented 9 years ago

@Kein Possibly the maximum streaming bandwith from akamai, not the source? I don't think Valve has any control over the message returned by Akamai.

Kein commented 9 years ago

When the streamer chooses resolution it changes accordingly in the manifest, but not the bitrate. That's weird. Source/streamer can stream even at 480@750Kbit/s and the broadcast still will deliver as 480@3500.

???