Roku (again)

**Peter** · 02-23-2021, 02:55 PM

We have tried adding mpeg support but there are issues with mpeg on the Roku. One of the issues was that seeking was not available when playing mpeg content.

**hsbrown2** · 03-01-2021, 03:00 AM

More Roku stuff...

If I have a video with Dolby Digital EX Mezzmo seems to transcode, but if I turn off transcoding, the video plays just fine. At least I *suspect* it is due to the Dolby Digital EX, as that is the only variable that seems to be different. What seems unusual to me as well is that the video has 2 audio tracks, and getting the ffmpeg info from Mezzmo looks like it reports them both as 5.1 (I believe DDEX is 6.1?).

Stream #0:1(eng): Audio: truehd, 48000 Hz, 5.1(side), s32 (24 bit) (default)
Metadata:
title : Surround 5.1
BPS-eng : 3325274
DURATION-eng : 00:56:06.405000000
NUMBER_OF_FRAMES-eng: 4039686
NUMBER_OF_BYTES-eng: 1399277692
SOURCE_ID-eng : 001100
_STATISTICS_WRITING_APP-eng: MakeMKV v1.15.4 win(x64-release)
_STATISTICS_WRITING_DATE_UTC-eng: 2021-02-25 03:17:42
_STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES SOURCE_ID
Stream #0:2(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s
Metadata:
title : Surround 5.1
BPS-eng : 640000
DURATION-eng : 00:56:06.432000000
NUMBER_OF_FRAMES-eng: 105201
NUMBER_OF_BYTES-eng: 269314560
SOURCE_ID-eng : 001100
_STATISTICS_WRITING_APP-eng: MakeMKV v1.15.4 win(x64-release)
_STATISTICS_WRITING_DATE_UTC-eng: 2021-02-25 03:17:42
_STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES SOURCE_ID

The Roku (or the Mezzmo app on the Roku?) seems to be aware that the TrueHD (set to preferred audio stream, if the matters) and EX exist, but I'm guessing it can't handle TrueHD and selects the EX audio, playing it just fine - but again, if I enable transcoding to the device, it just automatically starts transcoding. Any ideas?

**Peter** · 03-01-2021, 08:34 AM

When comparing the file to the device profile Mezzmo will use the first audio track so the file does not match and will be transcoded. You can change this in the properties of the file by selecting the second audio track on the Video tab and Mezzmo will use this to compare to the device profile. The Roku may not be able to play the first audio track so it selects the second one.

**hsbrown2** · 03-01-2021, 08:59 AM

If the preferred audio track is unsupported, Mezzmo will always transcode that track if transcoding is on, even if the second (or other tracks) *are* supported? I would sort of expect the behavior to first see if any audio tracks are supported without transcoding, and then transcode as a last resort. Is that behavior configurable at all? It wouldn't be terrible, but it seems like Mezzmo transcodes to stereo, at least with the Roku, not AC3 (which is fully supported).

What about E-AC3 (Dolby Digital Plus)? The Roku seems to handle it fine, and ffmpeg handles it differently than AC3, but I don't see any specific settings in any device profiles for it. Experimentally I added it to a movie (mkvextract-->ffmpeg-->mkvmerge), and it seems to downmix to stereo just fine on the Roku side - but I'm not sure how Mezzmo handles it on the back end, and whether or not it will send it to all Roku devices without transcoding.

I know this may be a Roku thing, but even when transcoding is disabled, I can't select any other audio tracks in the app even though I know they are supported, and I suspect the same may be true for external subtitles (although I haven't tested that yet). Is this something I am missing?

Cheers!

**Peter** · 03-01-2021, 01:15 PM

Mezzmo cannot get feedback from the device as to whether a file is supported so it is not possible to try playing the file with multiple audio tracks then transcode if it does not play. For the Roku AC3 is not supported in mpegts which is the default transcoding format so the audio is always transcoded to stereo.

For E-AC3, Mezzmo will read the codec name from the ffmpeg information and check if it matches the supported codecs for that container in the profile. You can edit the profile to add eac3 if that is the codec name reported by ffmpeg.

I think selecting other audio tracks only works if they are the same codec type. I have tested selecting audio tracks in the past with multiple stereo audio tracks. External subtitles will not allow selecting other tracks while the video is playing because Mezzmo only lists one external subtitle track.

**hsbrown2** · 03-06-2021, 01:11 PM

"Mezzmo cannot get feedback from the device as to whether a file is supported so it is not possible to try playing the file with multiple audio tracks then transcode if it does not play. For the Roku AC3 is not supported in mpegts which is the default transcoding format so the audio is always transcoded to stereo."

Got it. I'm slowly coming to the conclusion that the Roku isn't *really* designed for personal media collections, as much as it is designed to be an aggregate device for a plethora of online streaming services. While this could be a slippery slope with customers whose private collections contain director commentary tracks (which seem to most often be ac3), although Mezzmo can't get feedback from the device I would think it might be possible/plausible to evaluate the device profile and the available audio tracks, and if one is supported, play that, and avoid transcoding if one of the available tracks is supported (unless of course it is required for other reasons). Although this may be pointless, largely. Transcoding is fine - unless it's transcoding DTS down to stereo, which seems to cause all sort of problems for me.

"For E-AC3, Mezzmo will read the codec name from the ffmpeg information and check if it matches the supported codecs for that container in the profile. You can edit the profile to add eac3 if that is the codec name reported by ffmpeg."

OK, that makes sense. It does show as eac3, but I'm unsure if setting the default (preferred) track to the eac3 audio will stop it from transcoding. It doesn't have (what i would call) a dictionary reference, i.e. eac3 doesn't translate to "Dolby Digital Plus" when I look at the properties of the audio track in Mezzmo, so I wasn't sure is adding a format container for it would do anything.

"I think selecting other audio tracks only works if they are the same codec type. I have tested selecting audio tracks in the past with multiple stereo audio tracks. External subtitles will not allow selecting other tracks while the video is playing because Mezzmo only lists one external subtitle track."

Understood. This a small pain, though. If there are "forced" subtitles, and closed captioning style subtitles, both external, you can't have a choice of either/or. I'm not sure I'm down with burning in forced subs. Do you folks have a recommendation?

**ftanner** · 03-07-2021, 02:29 AM

Originally Posted by Peter

Mezzmo cannot get feedback from the device as to whether a file is supported so it is not possible to try playing the file with multiple audio tracks then transcode if it does not play. For the Roku AC3 is not supported in mpegts which is the default transcoding format so the audio is always transcoded to stereo.

For E-AC3, Mezzmo will read the codec name from the ffmpeg information and check if it matches the supported codecs for that container in the profile. You can edit the profile to add eac3 if that is the codec name reported by ffmpeg.

I think selecting other audio tracks only works if they are the same codec type. I have tested selecting audio tracks in the past with multiple stereo audio tracks. External subtitles will not allow selecting other tracks while the video is playing because Mezzmo only lists one external subtitle track.

As someone who is switching devices, over time, from Roku to nVidia Shield, does Mezzmo get feedback from those devices?

**Peter** · 03-09-2021, 08:43 AM

No, unfortunately there is no feedback from any device as to the supported formats and whether a file will play or not. Early DLNA specifications provided a mimetype list from devices but this was very general and did not specify codecs, bitrates and resolutions.

**ftanner** · 03-15-2021, 02:53 AM

Originally Posted by Peter

No, unfortunately there is no feedback from any device as to the supported formats and whether a file will play or not. Early DLNA specifications provided a mimetype list from devices but this was very general and did not specify codecs, bitrates and resolutions.

Sounds like it's time for an update to the DLNA spec.