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WiFi Bandwidth and Router considerations

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bhiga
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Default WiFi Bandwidth and Router considerations

Because Chromecast communicates solely via WiFi, the minimum sustained wireless bandwidth is critical for streaming quality.

This is usually not a problem for "normal" Chromecast applications that pull streams from the Internet - those services are designed to adapt to and scale with the available connection speed.

Content streaming from local devices is a different scenario altogether.

Chromecast doesn't necessarily work the same as traditional set-top media players (Apple TV, WDTV, Roku, etc) when streaming media from your phone/tablet/computer (device-local) and LAN-based (from a server) media can consume more bandwidth than you would expect.

Depending on where the media is located and how it is being sent to Chromecast, up to 3x the media's bitrate may be consumed (and required) on the WiFi network. If you have high bitrate media, this can easily overload an 802.11g connection or even an 802.11n connection.

Keep in mind that connection speed is not constant, and is limited by both your environment and your router.
Other nearby WiFi devices can cause interference, and the 2.4 GHz wireless band that Chromecast uses is "crowded" with many devices like cordless telephones and microwave ovens using overlapping frequencies.

Also, routers vary in the wireless speeds they can maintain. Just because you have a 802.11n 150 Mbps connection, that does not mean your router can truly sustain 150 Mbps throughput.

Better routers advertise use cases for "HD streaming" and have Gigabit LAN ports rather than 100 Mbps LAN ports found on cheaper models.
Just like a Gigabit Ethernet USB 2.0 adapter will never reach full Gigabit speed due the USB 2.0 bottleneck (480 Mbps), cheaper routers often are limited by their internal processor's lack of forwarding speed.

See the attachments for use examples and how the required bandwidth can multiply: Note that the 10 Mbps figure is just an example.
  1. Standard Internet stream example
    YouTube, Hulu Plus, HBO Go, VEVO, etc use this methodology
  2. Direct stream from LAN storage example
    Plex (from a local Plex server) and fling (from a desktop) work this way. Desktop and Tab casting from Chrome also uses this data flow.
    Data is sent from the LAN device via WiFi
    Chromecast receives data from the LAN device via WiFi
  3. Streaming from wireless device storage example
    Casting content stored on the device (device-local) from Avia or RealPlayer Cloud use this method.
    Data is sent from the casting device via WiFi to Chromecast
    Chromecast receives data via WiFi
  4. Forwarding from LAN storage example
    Casting content stored on a LAN device (DLNA, network share, etc) from Avia uses this method.
    Data is sent from the LAN device to casting device running Avia via WiFi
    Data is sent from the casting device running Avia via WiFi to Chromecast - this is the forwarding piece, data travels through
    Chromecast receives data via WiFi

To optimize available bandwidth for Chromecast:
  • Use an 802.11n dual-band router and put your other wireless devices on the 5 GHz access point whenever possible
    or use a separate WiFi access point connected to the wired network for Chromecast
  • Use wired connections for cast sources (server/desktop/laptop) wherever possible
  • Reencode high-bitrate media to lower bitrate (4 Mbps should be fine for most use)
  • Optimize Chromecast's ability to get a stable WiFi signal - move it away from the TV using the HDMI extender or an HDMI extension cable
    and/or move your router so it's closer to Chromecast (but not too close - too close can get into a "drowned in the noise" situation)
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Mini-FAQ: What's the big deal with root? || Mini-FAQ: Rooting with FlashCast || Assemble a powered OTG cable
WiFi Bandwidth and Router considerations || Not all 1080p/720p is created equal
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Asphyx
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Great Post this deserves a Pin!
 
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One big thing a lot of people don't realize is that wireless is half duplex...

If you have 2 devices on the same wireless network transferring data between each other, they will do so at half the speed, because only one device can talk at a time.

Say for example you have a PC wired to your router, and another PC on wireless.. You can copy a file between these computers at around 6MB/sec. Now you take the wired PC and connect it to the same wireless network instead. You will notice your copy speed is now around 3MB/sec.

If you are utilizing a wireless repeater to connect any of your devices to your wifi network, those connected to the repeater will experience the same halving of speed as well.

This is why having your local media source on a different band or wired helps so much.
 
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Quote:
Originally Posted by stevewm View Post
One big thing a lot of people don't realize is that wireless is half duplex...

If you have 2 devices on the same wireless network transferring data between each other, they will do so at half the speed, because only one device can talk at a time.

Say for example you have a PC wired to your router, and another PC on wireless.. You can copy a file between these computers at around 6MB/sec. Now you take the wired PC and connect it to the same wireless network instead. You will notice your copy speed is now around 3MB/sec.

If you are utilizing a wireless repeater to connect any of your devices to your wifi network, those connected to the repeater will experience the same halving of speed as well.

This is why having your local media source on a different band or wired helps so much.
Here's a scenario I would appreciate your comment on:
I have a bridge that connects to my main router. The media source (laptop) is connected direct to the bridge which is in the living room with my CC, the CC is wireless to the bridge. Will the distance the bridge is from the main router come into play if doing local media?
 
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Quote:
Originally Posted by sherdog16 View Post
Here's a scenario I would appreciate your comment on:
I have a bridge that connects to my main router. The media source (laptop) is connected direct to the bridge which is in the living room with my CC, the CC is wireless to the bridge. Will the distance the bridge is from the main router come into play if doing local media?
It shouldn't.... Unless the run to the main router is abnormally long.

My current setup has my plex server across the house from my TV room. Two out of three routers are upstairs and one is in the room with my plex server. All but one router is set up as access points. The distance combined between the three routers is roughly 200 feet. The distance is split between the three. Then roughly 25 feet from the closest router to the ccast. I have no more noticeable lag in the TV room than using the ccast in the back bedroom that the plex server is in.

I am sure if I was going to ping test this I would have a higher latency the further away it goes.... But like I said to real world use I can't tell it slows it down.

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bhiga
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Quote:
Originally Posted by rans0m00 View Post
I am sure if I was going to ping test this I would have a higher latency the further away it goes.... But like I said to real world use I can't tell it slows it down.
Exactly that. For home use, distance of wired connections doesn't matter much, as long as it's within specs and packets aren't being lost.

Distances for wireless connections, on the other hand, make a huge difference both in terms of latency and sustained transfer speed (bandwidth).
-- Brandon // Google Chromecast threads: FAQ - READ THIS FIRST! || Rootable Serial Numbers
Mini-FAQ: What's the big deal with root? || Mini-FAQ: Rooting with FlashCast || Assemble a powered OTG cable
WiFi Bandwidth and Router considerations || Not all 1080p/720p is created equal
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enricong
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I've noticed that video casted from a tab is barely smooth at 480p. I am upstreaming at approx 150kbps.
When I try 720p, it struggles at 300kbps dropping to 150 alot. Using "extreme" it about the same rate but more choppy.

I have a N network with my laptop connected at 300M. I can usually transfer files around 3-6Mbps.

I'm a little confused why with chromcast, I can barely maintain 150kbps. Even if you multiply by 3, I'm not getting over 1mbps.
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bhiga
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Quote:
Originally Posted by enricong View Post
I've noticed that video casted from a tab is barely smooth at 480p. I am upstreaming at approx 150kbps.
When I try 720p, it struggles at 300kbps dropping to 150 alot. Using "extreme" it about the same rate but more choppy.

I have a N network with my laptop connected at 300M. I can usually transfer files around 3-6Mbps.

I'm a little confused why with chromcast, I can barely maintain 150kbps. Even if you multiply by 3, I'm not getting over 1mbps.
It's likely not a wireless connection issue but rather a processing limitation on the computer you're casting from.

I just casted a 480p tab of full-tab video and my network utilization ranged from about 1.25 Mbps to bursts of 12 Mbps. The average was around 2-3 Mbps. What's the CPU utilization look like when you're casting?

Do other Chromecast apps like YouTube work okay with 720p or 1080p videos?
-- Brandon // Google Chromecast threads: FAQ - READ THIS FIRST! || Rootable Serial Numbers
Mini-FAQ: What's the big deal with root? || Mini-FAQ: Rooting with FlashCast || Assemble a powered OTG cable
WiFi Bandwidth and Router considerations || Not all 1080p/720p is created equal
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enricong
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Quote:
Originally Posted by bhiga View Post
It's likely not a wireless connection issue but rather a processing limitation on the computer you're casting from.

I just casted a 480p tab of full-tab video and my network utilization ranged from about 1.25 Mbps to bursts of 12 Mbps. The average was around 2-3 Mbps. What's the CPU utilization look like when you're casting?

Do other Chromecast apps like YouTube work okay with 720p or 1080p videos?
CPU is an i5-2520M. Utilization is only around 20-30%. I've tried with and without Nvidia GPU.

Youtube seems ok at 720 and 1080, however, I thought that youtube videos get streamed directly to chromcast vs the laptop.
Also, when I stream a youtube video, I have no idea if chromecast sticks with my browser setting or figures out its own quality setting based on bandwidth. I thought it was the later.

Are you using regular Chrome, or Chrome Canary?
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bhiga
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Quote:
Originally Posted by enricong View Post
CPU is an i5-2520M. Utilization is only around 20-30%. I've tried with and without Nvidia GPU.

Youtube seems ok at 720 and 1080, however, I thought that youtube videos get streamed directly to chromcast vs the laptop.
Also, when I stream a youtube video, I have no idea if chromecast sticks with my browser setting or figures out its own quality setting based on bandwidth. I thought it was the later.

Are you using regular Chrome, or Chrome Canary?
Interesting... You're correct that YouTube grabs the stream directly and determines the best settings. But if you have a 1080p TV and YouTube is pulling a 480p stream, it'll definitely be noticeable - especially on things like text.

My Chrome is Version 32.0.1700.107 m
and Google Cast Extension is 14.123.1.4

My system is relatively old, but it was a powerhouse in its day and still fine for what I do with it.
Windows 7 Professional 64-bit
Dual Quad-Core AMD Opteron 8389 2.9 GHz
32 GB RAM
AMD Radeon HD 7750
-- Brandon // Google Chromecast threads: FAQ - READ THIS FIRST! || Rootable Serial Numbers
Mini-FAQ: What's the big deal with root? || Mini-FAQ: Rooting with FlashCast || Assemble a powered OTG cable
WiFi Bandwidth and Router considerations || Not all 1080p/720p is created equal
Follow the rules / Use 'Search' before posting / Post in the correct sections / Do not spam the board / Press thanks, don't post 'Thanks'

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