Consistently disparate playback results on same file (MP4 versus MKV)

General Discussions
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I know, that sounds weird, “consistently disparate”, but hear me out.

I recently transcoded some media files whose video bitrates were a bit high for my taste; audio was fine, so I decided to keep that as-is. Using handbrake, I converted each file’s video to HEVC, reducing the resolution from 1080 down to 720; for the audio, I did a simple pass-through, keeping the original audio stream in the new MP4. I’ve done this thousands of times, and I know it works fine.

When I went to play the resulting files on my Roku Ultra, I immediately noticed a one-second audio/video sync issue. I jumped to a different section of the file, restarted Plex, then rebooted the Ultra - all attempts resulted in the same one-second video delay. To verify the file’s integrity, I used a media player (zoomplayer) to play the files locally on my computer, then played them on my computer from my NAS - both methods played just fine.

When I attempted to play the same files on my computer using PlexWeb, the files would refuse to play automatically. I had to manually jump to a point on the timeline, but I then saw the same one-second delay. However, when I played the file using Plex Media Player, the files played perfectly. I then tested the files on my iPad, and saw no sync issues there either.

To test even further, I re-muxed one of the files using the transcoded video stream plus the audio stream from the source file using MKVToolNix (an app I use almost every day), and the resulting MKV file played flawlessly across all my devices. Same video stream, same audio stream, different container.

I’m pretty sure this might be an issue with the source files, as I’ve never come across this kind of thing before, and as I mentioned, I use the audio pass-through in handbrake all the time. Has anyone else ever experienced this kind of

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  1. HEVC is a PITA.
  2. HEVC on a Roku is a Major PITA.
  3. HEVC on a Roku 4, Ultra, Premier is a LOL-Fest.
  4. HEVC on a Roku (any) in an MP4 file is a ROFLOL-Fest.
  5. If you want a smaller file whacking the resolution from 1080p to 720p is a great way to destroy your visual experience.
  6. If you want a smaller file half the bit rate of the 1080p file and run some previews - adjust for your eyeballs.
    6a) My eyeballs stop seeing much difference in quality at bit rates above 3750-4250Kbps - YMMV.

The Handbrake Guide in my signature may be of some use.

Notable Mention:
Anything newer than a Roku 3 introduced ‘the lips and the words not living in the same zip code’ bug. Roku is in the bidness of selling Rokus - not in the bidness of fixing broken Rokus. Roku is clinging like drowning sailors to this notion that one FW will fit all their boxes - but the sharks of reality are eating them left, right and center.

To their credit they don’t want to blow up their only reliable unit - Roku 3 - with a FW update that would kill a Roku 3 while fixing all newer models so all newer models have ‘the lips and the words not living in the same zip code bug’. You found this bug and apparently you found a bit of a work around.

Stick with 264 for another decade at least - perhaps by then it won’t be such a PITA.
Stick with MKV files if you want to embed subtitles
Experiment with containers/audio and if you can find something that works and keeps the lips and the words living in the same part of town - use that.

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While I appreciate you taking the time to write a response, your post really only amounts to a lot of judgement. I didn’t ask for opinions about my preferred resolutions, hardware devices, or codec preferences, I asked if anyone has ever witnessed the behavior I was describing. I’ve been re-encoding media for my Plex library ever since I started using Plex years ago; I’ve gone through a procession of Rokus (2, 3, Stick, 4, Ultra) and have finally settled on the Ultra as my favorite, for multiple reasons. My priority is filesize to video quality ratio, so HEVC plus Roku Ultra equals my perfect setup. I love Roku machines, and I think HEVC is great for keeping filesize down while retaining excellent video quality. You might not agree with that, but as you yourself are fond of saying, you don’t have my eyeballs.

To reiterate: I have never had this particular experience with any of my other MP4 files, where the file plays incorrectly (yet in the exact same manner) on several Plex clients, but plays fine on others. I must remind you here that PlexWeb also had trouble playing the file, so it’s not really a Roku problem. The Ultra, it must be said, uses hardware decoding to process h.265 files, while PlexWeb needs to transcode down to h.264.

So I think I’ll stick with HEVC encoding because it’s the best solution for me; as I said, I’ve been doing this for years, so I’m not unfamiliar with the mundane details of transcoding, media containers, resolutions, and codec issues. 98% of my TV show files are h.265 MP4 files, and they all play flawlessly. For my movie library, I typically have h.265 MP4 video streams, multiple audio streams, and embedded subtitles in MKV containers. Through meticulous trial and error, I have settled on my own perfect handbrake formula - that again, is specific to my needs and requirements - and I am perfectly satisfied with the h.265 codec. My OP has to do with particular media files that behave differently from my thousands of other files, which have all been encoded using the same methodology and settings, and as I mentioned I suspect the source files, and my workaround works well enough for now.