m4v vs mp4

[Sill]

I've been going through the files on my iTunes movie library, and I noticed that out of all my mp4 files, a couple of TV show episodes had .m4v extensions instead of .mp4. In my research to find out the difference, I read an earlier thread here, which said that movies in .mp4 format would not allow iTunes to recognize multi-channel audio. Specifically:

The appleTV needs the .m4v file extension to know how to deal with the AC3 in the mp4 container. Thats why the appleTV preset changes it in the destination field.

I've had issues with audio playback on iTunes rips, specifically movies that should be in 5.1 are coming across in 2.0. I thought it was one of the growing list of issues with my Sonos 5.1 system, as the industry passes it by with higher surround standards, but then with my new aTV 4K I get perfect 5.1 out of Netflix and all of my non-DTS movie discs.

so... I checked my file info coming across from my movie server to Infuse, and saw every movie was shown in "AAC 2.0" I know most were ripped to 5.1, so where did the audio go? Is it the fault of something as simple as the file extension? If so, should I re-encode in Handbrake, or should I just change the extension name? If its not the extension, where did my other audio channels go?

 

[HobeSoundDarryl]

If you properly have the ac3 track in the file, just change the extension to .m4v. If you ripped it but opted to not include the ac3, the stereo AAC is all that can be played (because it's all that is there). To do the latter, you’d have to manually jettison the ac3 track if you ripped via an tv preset. Odds are you probably did NOT do that, so it’s probably there. Change the extension of something with 5.1 and see, or HEAR, for yourself.

 

[Ritsuka]

"m4v" is a different brand with some additional features made by Apple. But iTunes and QuickTime doesn't care about the file extension at least since 7 years ago.

 

[Sill]

I changed a couple of files to m4v and nothing changed on the audio. Everything still comes up 2.0.

I think I may have not set my encodings correctly. Even though I have 5.1 in the audio track, it shows "Dolby Prologic II" under the Mixdown menu. It should show 5.1 there too, shouldn't it? I may have seriously screwed this up.

Over 150 movies... my head hurts just thinking about doing all of this over. Between this and Sonos not liking DTS I may just go back to physical discs and a proper home theater.

 

[HobeSoundDarryl]

If you have (the free app) Subler, open one of the files in which you expect 5.1 and look at the list of tracks. There should be an audio track called "stereo" and another called "surround." Over in format (column), the description next to "surround" should be "AC3, 6 ch". Is it?

And FYI: there are blue check boxes at the far left in the Subler window. The "surround" row should be unchecked.

What "mix down" menu are you referring? What program?

Here's an example of how the above should (generally) look within Subler (especially note that "Surround" row)...

 

[Sill]

The mix down menu is in Handbrake.

I could yell right now. Out of all the movies I checked, exactly one has a surround row in Subler. And that one is missing the Stereo row you said should be checked.

Grrrr...

 

[HobeSoundDarryl]

It's increasingly sounding like whoever encoded them did not do it properly for these purposes. If you did it from discs, you'll probably have to repeat the process if you want to get TV files encoded properly. I suggest doing just ONE disc that definitely has a 5.1 track, choosing the right preset, and encoding just a single chapter (so you can get a resulting file very quickly). Then check it in Subler and it should look pretty similar to the image. Once you know you have the encoding properly, you could then go to the trouble of redoing all of your discs though that will be a BIG job.

FYI: If I open known 5.1 movies in HB right now, it doesn't show them as having a 5.1 surround track either. Instead, it's showing just a AAC (mix down) stereo track and an AC3 Stereo track. But Subler shows it as expected.

If you sampled a bunch of them in Subler, they have to look pretty similar to that picture if they are properly encoded. The checked "stereo" row "AAC 2 ch" is the default audio track so it will play on mobile devices like iPhones & iPads. The unchecked "surround" row "AC-3, 6 ch" MUST be there or the file lacks a 5.1 surround track.

 

[Sill]

Yeah it looks like I'm going to have to redo all of these. That's going to take weeks.

Out of curiosity, if I redo these, can you recommend settings? I'll most likely use MakeMKV and Handbrake, unless there is something better out there. I currently have the aTV4K, plus the SonosHT. DTS won't work, so I'll need DD5.1. However, the new aTV supports DD+, which we just might get out of Sonos one of these years, so is there a way to rip 7.1 info (if its on the disc) and have it available, but be downwards compatible with DD5.1? For that matter, can I pull TrueHD off the disc but have the 4K output 5.1 from it to the Sonos?

I apologize for all the questions, but I could seriously lose my mind with all these encodings and surround "standards". Sonos makes it worse.

 

[HobeSoundDarryl]

That combo should work well. Key will be choosing the right preset so that you don't repeat any mistake from the first round. Again, that one chapter test approach could set you up with a "debugged" step-by-step process.

Note that with a 4KTV, you can give consideration to embracing h.265, though that will slow down the compressing. And if I was redoing everything from scratch myself, I'd probably seriously consider h.265 encoding and probably appending one of the better audio tracks too, just for future proofing of the files. In other words, I'd probably encode for h.265 AND append a DTS or TrueHD track with the DD and AAC stereo tracks. That may be overkill and I wonder if TV will EVER embrace DTS or TrueHD, but I might go to the trouble anyway if I was starting over from scratch now.

h.265 should yield a smaller file but appending DTS or TrueHD might beef it back up again for little net again (except you would already have those audio tracks in there, ready to be used should the time come... instead of potentially having to do this from disc yet again should such an option present itself somewhere further down the road).

Conceptually, down the road maybe Apple DOES bring on DTS and/or TrueHD options, at which time, it would be relatively easy to potentially go in and jettison the DD track to shrink the file size.

Now that said, a simple tutorial from disc to mkv to h.265 I can't offer as I haven't made this move myself. So hopefully, someone will step in and show you the way there.

 

[priitv8]

You can rename mp4 to m4v and vice versa, will make no difference.
Problem with DD+ is, especially in HandBrake, that there is no encoder for it. So you can not downconvert other 7.1 streams into DD+7.1
Curiously, I also have not managed yet to pass it through in HB. DTS (core only!) passthrough goes also in HB.
I have to use Subler to append E-AC3 (DD+) track, if I have it in source.
PS You would also want to run the file optimization (cmd+O) again, every time you add or delete audio tracks in Subler, to make sure the file will load fast without spinning the cogwheel for minutes.

Here's an example of how the above should (generally) look within Subler (especially note that "Surround" row)...

Leaving the Language setting for chapter track as Unknown made chapters disappear in tvOS. Since then I always set it to English (suber will do it automatically when you import from file or chapterdb.org). You supposedly can also have chapter titles in different languages if you will.
Has this been fixed now?

 

[Rigby]

Curiously, I also have not managed yet to pass it through in HB. DTS (core only!) passthrough goes also in HB.

This is because Handbrake's muxer currently doesn't support E-AC3 (see here). It's a shame really, since E-AC3 not only supports 7.1, but is also more efficient than AC3 and supports bitrates above 640 kbps (which provides near-lossless audio quality without blowing up the file size like lossless codecs do), while still being natively supported by the ATV4/4k. It's really an ideal codec for re-encoding to a more compact format.

 

[priitv8]

This is because Handbrake's muxer currently doesn't support E-AC3 (see here).

Well, that explains it. E-AC3 is also important, because if and when Apple decides to implement Dolby Atmos support, I would bet it will be on E-AC3 and not the TrueHD.

 

[cynics]

Using handbrake different movies can benefit from different settings. Like you may want to denoise an old movie since it will compress much better plus clean it up.

I would suggest experimenting with a couple movies and see what works best for you. Also make sure the output plays on ALL the devices you ever intend on playing them on. You can easily make a file too complex for certain devices to decode.

 

[kiranmk2]

If you are happy with the video quality of your current rips then when going back to re-rip the AC3/DTS tracks you could rip with extremely low video quality settings and then use Subler to transfer the AC-3 track from the low quality file to the high quality file. This is what I do if I forget to include an audio track on a rip and it works very well - extremely low video quality encodes are often 10x faster than 'regular' encodes.

I did wonder about using HEVC to re-encode my old DVD library, but from my tests HEVC isn't so efficient for DVD resolution and I only saved ~20-30% space. So, while I rip encode new things in HEVC I'm happy to leave my old encodes in AVC.

 

[priitv8]

If you are happy with the video quality of your current rips then when going back to re-rip the AC3/DTS tracks you could rip with extremely low video quality settings and then use Subler to transfer the AC-3 track from the low quality file to the high quality file. This is what I do if I forget to include an audio track on a rip and it works very well - extremely low video quality encodes are often 10x faster than 'regular' encodes.

Depending on the source file, I tend to avoid HandBrake altogether, if I only need the audio track(s) from the rip. That's because HandBrake does not know to pass video stream or leave it out, it always insists on encoding video.
The simplest will be to use mkvtoolnix to encapsulate necessary audio/subtitle/chapter streams into MKV and then add them via Subler, as it is able to open and parse MKV file. That saves time needed to encode even low-quality video stream in HandBrake.
More adventurous users will find that command-line ffmpeg is able to manipulate any media file in many useful ways, including but not limited to what has been described above.

 

[Sill]

If you are happy with the video quality of your current rips then when going back to re-rip the AC3/DTS tracks you could rip with extremely low video quality settings and then use Subler to transfer the AC-3 track from the low quality file to the high quality file. This is what I do if I forget to include an audio track on a rip and it works very well - extremely low video quality encodes are often 10x faster than 'regular' encodes.

Are there any steps to take to sync the audio and video?

 

[priitv8]

Are there any steps to take to sync the audio and video?

Normally not, if the tracks come from same source, have same framerate and timings.