@mj34hig44 I agree with you. We dropped Dish Network close to 10 years ago. We have excellent OTA, with around 50 channels/sub-channels in the Seattle area. We subscribe to Prime, but it's mainly for their shipping and the streaming is just an extra perk. I have HBO Max, but only because it comes with my cell phone plan. I have 5 hard drives on my "server" that I rip all my purchased DVDs and Blu Ray discs to, and that is over 90% of our TV watching. I really wish Roku would make a top end player that would handle my media like the Shield does, but that's probably a pipe dream. Likely not enough demand in their market surveys.
Interesting. I tested the same settings on a sample. An .mkv played correctly, and an identically constructed .mp4 did not. I then reversed the stream order on the .mkv to where the AC3 track was ordered first and was marked as the default. It did not play correctly. So it seems that RMP correctly plays the default audio track on .mkv files, but it does not for .mp4s.
I don't have a lot of MP4 files, compared to my MKV and TS files, and those I checked are mostly AAC audio. But I did find some that have AC3, mostly recorded OTA TV that I likely used either Handbrake or VideoReDo (probably the latter, since I remove commercials from everything). What I found is that some files are not even displayed in RMP when I use folder view from my server (which is supposed to bypass the player not showing files it considers unplayable). I can play those titles just fine on the computer. But other MP4 files with AC3 audio appear, and in my quick testing using my Premiere 3920 connected to a Vizio 4K TV everything plays fine. So I can't duplicate the problem, at least with my Ultra or Premiere players. I must point out the Premiere is on the Roku beta test stream, so it's on a build number that I can't disclose. Now there's no way of knowing if that version has fixed the problem, as I don't hear any problems with my Ultra 4800, which is not on the beta stream.
One difference that you're seeing may be the sample rate. RMP (per the developer docs) supports an audio sample rate of only 48k on MP4s. 44.1 and 48k are supported on MKV. I know the few MP4s I had that were 44.1 terminate without playing at all.
Interesting theory about the sampling rate. I just looked at one of the files that doesn't even show up in RMP, and it's 48 KHz. I found 44.1 KHz on an MP4 with AAC audio, and it played fine. I just found another MP4 with AC3 audio and 44.1 KHz sampling, and it plays as well. Another MP4 with AC3 and a 48 KHz rate doesn't even appear. At least with my Premiere, it's not the sampling rate. Sheesh...
I have gained a newfound appreciation for the media player on my main system. It plays all the .mp4 files my DLNA server can throw at it without complaint... all sampling rates, bitrates up to 448k, all frame rates, no problems with subtitles, no buffering... I probably should not have taken the Roku path as a way to try to extend the useful life of the other two TVs.
Well, Roku devices are great for what they are designed for, which is a) being inexpensive and b) streaming from online providers. My $150 Shield doesn't do that any better than a Roku, and depending on the provider (looking at you CBS) the Roku offers 5.1 sound while Android devices are stereo only. DLNA playback was an afterthought, and to be a true home media player it would require some significant upgrades. My guess is more than 90% of Roku users never stream anything other than Netflix, Prime Video, YouTube, HBO, and the other big online names. We unfortunately are a small subset of users, and just don't make enough of a dent in their thought process. And frankly, to be as good a local player as an Nvidia Shield, the price would likely get close to the same ($150), so lose the price competitiveness. And in this area, price is king. I don't know what your main system media player is, but chances are it was designed with local playback in mind, so development was guided in that path. There are many sub-$50 Android players that will work with local media better than a Roku, solely because of the expanded codec and container support. Those devices might not work as well on the major online sites, and in some cases might not offer them at all. But the Android underpinnings provides the basics needed for playing the media. And of course, many are manufactured in countries that aren't too worried about actually paying for a license to support a particular codec. 😄
Seven months later, AC-3 playback in the Media Player works again with 10.5.0 - build 4201-91 on the Roku Premiere 3920X.
Concur that the issue is resolved for me as well with model 3810X. Both of my devices are updated to OS-10.5 version 4201-50 / RMP version 5.5 Build 12 and are functioning as expected.