MPEG-2

All posts tagged MPEG-2

Back in Cord-cutting status report #1, I ventured this opinion:

“But it seems to me that the single most cost-effective, option-expanding move is to wire for Ethernet. The huge increase in bandwidth should immediately benefit the Roku and Raspberry Pi in faster loading time, responsiveness and higher resolutions.”

XAV101

XAV101 Netgear Powerline adapter

That is not as clearly true for us now as it once might have been, for a couple of reasons.

One, I physically placed a Windows Media Center PC in the theater room so it could be directly connected to the Raspberry Pi computer, rather than have them connected by Ethernet. (The WMC/Pi functions as a DVR with no monthly fees.)

Two, the den (my wife’s domain) is getting a polished, ultra user-friendly DVR, the TiVo Roamio OTA ($15/mo subscription). I am also putting a Mohu Sky 60 antenna on the roof. If the Mohu/TiVo combo is satisfactory for her, we will try cutting cable TV entirely. The TiVo’s internet connection, needed for program listing updates, will also be via Powerline.

With those two moves, Ethernet wiring takes a lower priority, though it would still be nice. Instead, we use Powerline to get internet to all our devices.

Powerline (aka HomePlug) uses your house electrical wiring to connect Ethernet-ready devices.

Plug one adapter into an AC wall socket near your internet modem/router, and connect the two with an Ethernet cable. Plug the other adapter into a socket near where you need internet, then connect it to your device with another Ethernet cable. You then have a “wired” Ethernet connection over your house wiring.

Five years ago, I was in the market for a Blu-ray player with built-in Netflix for our theater room. The choice was either a player with built-in wifi, or a cheaper “networked” model (wired Ethernet only). I chose the latter. But we had no internet connection in our theater room. To make it work, I spent the savings on a pair of Powerline adapters, shown at left above.

Netgear XAV101 utility

Click to enlarge

The bandwidth (“Link Rate” on the screenshot) is not as high as with Ethernet cable, which is typically in the gigabit range (1000 megabits per second, abbreviated Mbps).

At right is a screenshot from the Netgear XAV101 Configuration Utility software.

As you can see, the adapter connected directly to internet (Device 01) has a maximum design capability of 200 Mbps. In theory, this would be more than adequate for any media we currently use.

The adapter in the theater room (Device 02), is able to achieve a bandwidth of only 55 Mbps (the rate does vary from minute to minute and hour to hour). Why so much less than the nominal 200 Mbps? It depends on the adapter’s electrical “nearness” to its mate, and noise levels in the wiring.

Our theater room appears to have been a last-minute add-on in 1978 when our house was built. I assumed from the sometimes flaky behavior of an X10 ceiling fan switch in there that the electrical path to it was a bit circuitous. (X10 is a home automation technology that also uses house wiring.) The ceiling fan problem was largely solved by plugging our refrigerator, the theater room equipment. and the den TV into X10 noise filters. (X10 and Powerline do not interfere with each other.) Still, the theater room has lower put-through with Powerline.

Our theater room Powerline (physical) bandwidth of 55 Mbps is comparable with our wifi’s design limit of 54 Mbps. But both Powerline and wifi send actual data at not even half that rate at best, so their true throughput is around 20 Mbps, tops. (Newer standards of Powerline and wifi improve on that considerably.)

But that is sufficient for most streaming. Netflix recommends a mere “5 Mbps or more for the best audio and video experience”. We have had few problems with streaming Netflix. Heck, we even downshifted last year from 15 Mbps to a 5 Mbps internet plan with the cable company, and still rarely if ever see any buffering or sub-par video.

Broadcast HDTV recordings (e.g., on a Windows Media Center PC) are another matter. They can require as much as 20 Mbps bandwidth, which is at the limits of our Powerline connection. In practice, I found that trying to play these recordings on the Pi from a Powerline-connected PC was frustratingly inconsistent. Turns out that video encoded in the MPEG-2 format, such as broadcast TV, is unforgiving of transmission errors, which makes even faster Powerline and wifi problematic. Ethernet wiring is one solution to this problem.

Another solution is to do as I did, place the PC in the theater room, and connect it to a gigabit switch with the other devices. Bandwidth limitations and transmission errors are non-existent. The Powerline adapter, plugged into the switch, provides internet access to the Blu-ray player, PC, Raspberry Pi, and a Roku 3.

I recently acquired another Powerline adapter (Device 03 above) for the den, a used Netgear XAV2001, compatible with our existing XAV101s. As you can see, it achieves a much higher physical bandwidth (100+ Mbps) than the other adapter, due to the den’s more standard electrical wiring. (Cheaper and higher bandwidth Powerline adapters are available; see the TTM Amazon Store for a couple of choices.)

Another reason I like Powerline is to keep multimedia devices off our wifi router, which operates in the same frequency band as our video sender.

Powerline is very secure. Our older model uses 128-bit AES encryption. According to EE Times, to crack it with a supercomputer brute force attack would take longer than the age of the universe. I don’t worry about the weird kids on the block (at least not over this).

Don’t get me wrong, Ethernet wiring is the ultimate in bandwidth and simplifies everything. Certainly new houses should be wired, and it might well be worth it for you to wire an existing home. But Powerline can be a good alternative to wifi, though not as fast and clean as Ethernet.

I’ll post about the TiVo after I set it up and try it out this weekend.

mediabrowserI have explained how the free media player software, Plex, is able to serve the movie, TV and music content on our PCs to our Roku boxes and a Raspberry Pi computer (see previous post, 007 24/7 on Plex Media Server).

But I must let you know about a Plex problem with movie and TV content ripped directly from DVDs into MKV format.

As noted before, MKV is a container format, and in this case, what it contains is the original MPEG2 content from the DVD. Broadcast digital TV is also in the MPEG2 format.

Newer Plex software releases seem to have trouble transcoding some of these MKV files for the Roku Plex channel. When our PCs (running Plex Media Server software) stream these MKVs to any of the Rokus, there is a bit of juddering and pixilation. I get the same result with 802.11g wifi as with wired Ethernet. It’s not a CPU issue, since both a weak Celeron-powered PC and a powerful quad-core PC produce the same result.

Plex’ original transcoder was the free ffmpeg software tool. But Plex’ latest software releases rely strictly on the new Plex Transcoder, based on ffmpeg, but rewritten by their team. The way the Roku Plex channel handles the new transcoder may be the cause of the problem, and I have reported it on their PlexPass forum.

(Here is Plex’ release note for the 0.9.10.0 version, Sep 8, 2014: “The legacy transcoder, which is available as an option in some Plex clients, will be removed soon. Please be sure to report specific cases where you still see better results when using it.”)

Now, it is true that once these MKVs are converted to MP4 using Handbrake (with Rokoding settings), they play perfectly on Plex. And MP4 file sizes are smaller, and the files are more usable with other devices. But I am a bit lazy, and would prefer not to convert if I don’t need to.

I have discovered another entrant in the media player system arena that can transcode and stream these MKVs to Roku perfectly: Media Browser. Media Browser uses ffmpeg as its transcoder.

MB also uses ffmpeg to transcode Windows Media Center broadcast TV recordings (.WTV format), served to MB by free ServerWMC software. As we noted at the top, broadcast TV is MPEG2. You would probably need a powerful processor and an Ethernet or switch connection, and maybe a Roku 3 for this to even have a shot at working acceptably.

(The Raspberry Pi decodes MPEG2 video content in hardware, with a one-time $4 MPEG2 license. Thus it handles MKV and WTV files with ease. It can also act as a Plex client with the PlexBMC beta software.)

Fortunately, Media Browser works with media organized to Plex standards, so no changes to your file system are needed. Setup is different from Plex, so you have to spend a little time with it initially. But it is great to see that Bond marathon playing perfectly on Roku, and not just the Raspberry Pi.

Plex and Media Browser server software coexists just fine on our PCs. So I use both. I prefer Plex’ presentation, but MB is fine.

Eventually, I’m sure Plex will fix their transcoder/Roku problem, but it’s good to have an alternative. Did I mention that Media Browser is also free?