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Combining bitrates and video dimensions
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Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times Was thanked: 4 time(s) in 3 post(s)
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Until now I have always webcast live in SD, at 720X480 (480p) with a bitrate of 650 kbps, to make sure viewers with slower connections do not face any problems. Recently though I am starting to get requests to broadcast in HD, but want to make sure that slower connections do not get left out - which means ABR.
Here's what I am considering for my 3 ABR uploads: 1. 2000 kbps at 1280X720 (ie. 720p) 2. 1000 kbps at 1280X720 3. 650 kbps - should this also be 1280X720 or should this last one's dimensions be smaller to accommodate the slower connections?
Questions... 1. If the bitrate is kept at 650 kbps will 720p require more bandwidth that 480p video? (I assume - yes?) 2. Will the slow connection folks be able to watch 720X480 better/smoother than 1280X720 sized videos the same as they did before?
Any advice would be most welcome.
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Joined: 10/7/2015(UTC) Posts: 635 Location: California
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The main issue will be how much upload speed you have at the location(s) you'll be streaming from. Perhaps you should take this in two steps.
First add stream at 1280x720 at 2000-2500 kbps for HD viewers and keep your 480p stream at the 650 kbps bit rate for viewers with slower connections. You might want to consider a 16:9 resolution on the 480p stream.
Then if all goes well, add a third stream though I wouldn't stream 1280x720 at 1000 kbps. That's well below the YouTube recommended minimum of 1500 kbps.
Or consider a 1980x1080 stream (minimum 3000 kbps) and the lower res stream for viewers with slower connections.
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Joined: 8/2/2013(UTC) Posts: 1,072 Location: Fairhope, Alabama USA Thanks: 553 times Was thanked: 200 time(s) in 166 post(s)
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I have some answers or maybe just opinions.
1. 650kbps is 650kbps. But 720p will not look as good as 480p at this bitrate. 2. Why change what works for these folks?
Some thoughts...
Make sure you have enough upload bandwidth to send three streams.
Consider using a CDN that will take a single stream from you and restream it at different resolutions and bitrates. YouTube does that for me. I send a single 720p/2500kbps stream and YouTube restreams it at 144p, 240p, 360p, 480p and 720p and allows the viewer to chose what works best for them.
Hope this helps.
- Tom
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1 user thanked sinc747 for this useful post.
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Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times Was thanked: 794 time(s) in 589 post(s)
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Hi Pesi
yep as Tom said, you gotta change your streaming platform. I already explained this to you in one of your very first post in the forum! I told you to use a platform that handles "MultiScreen transcoding" so that with a single 1080p stream, your viewers can have automatic selection by their device between 144p, 240p 360p, 480p, 720p and for sure 1080p depending on their available bandwidth and screen resolution. Besides the platforms that do multiscreen also do ABR, e.g. Adaptive Bit Rate streaming which is very important to avoid buffering. It means that even if a viewer has variable bandwidth, his player will automatically switch to an inferior quality for a moment so that the viewing experience is not stopped (with this annoying buffering symbol). As soon as he gets more bandwidth, the player comes back to best quality as possible.
Have a good day Guillaume
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Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times Was thanked: 4 time(s) in 3 post(s)
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Thanks guys for all your great suggestions. I will (usually) have enough upload speed - most hotel venues these days offer huge upload speeds if requested. What I finally decided on was... 1080p at 3000 kbps 720p at 1500 kbps 480p at 650 kbps
Using ABR - and yes, my CDN (its not YouTube) does offer the ability to take my HD stream and restream it at the different rates. Thanks again guys - fingers crossed for my first HD webcast! :-)
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Rank: Advanced Member
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Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times Was thanked: 794 time(s) in 589 post(s)
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6000 kbit/s is recommended for 1080p 1500 kbit/s is the minimal requirement for 720p, the moving shots or the transitions effects won't be good with such a bitrate. 3500 is recommended for 720p
If your CDN can transcode, then stream a single 1080p at 8000 kbit/s and you will have TV quality
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1 user thanked DWAM for this useful post.
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1 user thanked elvis55 for this useful post.
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