Quality loss to encode DD from DTS for ATV

Discussion in 'Apple TV and Home Theater' started by TrackZ, Apr 12, 2012.

  1. macrumors member

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    #1
    I'm looking to convert my video library for Apple device use, with an Ipad 3 and Apple TV 3. This is primarily converting blu-rays, many of which have DTS-MA/HD audio.

    Handbrake allows re-encoding DTS core, often at 1.5 Mbps, to DD at 640 kbps. I'm curious if anyone has done any dedicated listening/analysis on that quality loss. Do you find the tracks perceptibly different? Is there a discernable qualify difference to do this?

    On the one hand I don't like doing this and so I think to just get a Dune, but on the other hand, given we use all Apple devices in our house, using iTunes and getting everything compatible in that ecosystem has tremendous benefits to usability and access. I'm struggling to make the final commitment to start encoding and toss those 100% video/audio quality BD main movie rips though.
     
  2. macrumors 65816

    Sedulous

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    #2
    I never noticed a difference but you might. Do a test run to compare the audio from the bluray playback with that of the ripped/transcoded m4v.
     
  3. macrumors member

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    #3
    I can tell a difference but not to the point that I can't stand to watch a movie. What I mean to say is, the DD sounds perfectly fine on the movies I have done but of course lossless is better. Just like the 4gb 720p file I make from a 30+ gb bluray is not going to look as good as the actual disc, but it's pretty damn close (hell of a lot better than DVD). Now that the ATV3 is out, 8gb 1080p trancodes look even better. When you throw in the convenience factor of having the movies in itunes, I can easily overlook the slight differences in sight & sound. I still watch blu on my reference system when I want the best audio & video though.
     
  4. macrumors 6502

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    #4

    It all depends on your audio setup and your ear to pick up discrepancies. There will always be something loss when doing a conversion. I have a pretty high end system and I can't really tell the difference between the original dolby track and the converted ATV file. Now I can definitely tell the difference between a bluray True HD/DTS-HD track when compared against a ATV file.
     
  5. macrumors 68020

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    #5
    Here is a thought .... add a third DTS Passthru audio track to the existing presets AAC and AC3 Tracks. That way you are future proofed ... for instance when xbmc releases their nightlies in their trunk repo (yes, xbmc trunk does play back DTS in an mp4).

    That said, I personally haven't noticed much if any difference but ... its always an option in HB.

    If your worried, don't be, the atv still will use the second AC3 Track and the iPad will use the first AAC track as always and just ignore the third DTS track. Once you compile or wait for the xbmc nightlies to come back around or other players are updated to use DTS in a MP4, you can always select that third DTS track if you want the original source audio. Win-Win.
     
  6. macrumors 68020

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    #6
    I brought this up before but it seems relevant to your comment. When I added DTS-HD and DTS tracks to a HB ripped mp4 the aTV 3 would not play the file. I got an error saying the file was unavailable. When I removed both DTS tracks the file played fine. So it's worth a try but try it on a single file first. If it is successful, please let me know as I would love to future proof things by adding dts tracks below the AAC and AC3 tracks.
     
  7. macrumors 68020

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    #7
    I may have spoke a bit to soon. testing now to see if the atv will still take it ... it should. but maybe not.
     
  8. macrumors 68020

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    #8
    Keeping my fingers crossed!!:D
     
  9. macrumors 68020

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    #9
    I stand corrected. the atv will not accept a movie that has a dts track in a mp4. My apologies for an errant earlier statement.

    That sucks.
     
  10. macrumors 68020

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    #10
    +1
     
  11. macrumors 6502

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    #11
    I can confirm a DVD encoded with High profile preset with AAC as track 1, AC3 as track 2, DTS as track 3 and commentaries etc as track 4 etc plays back fine on an ATV3 (although the DTS track isn't recognised). All the other sound tracks work fine.
     
  12. macrumors 68020

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    #12
    Did you use DTS passthrough?

    I also used High Profile and the same format as you without success. I did have a DTS-MA track before the DTS track. Could that be it?
     
  13. macrumors regular

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    #13
    Just to be clear, you are talking about standard DTS, not DTS-MA.
     
  14. macrumors member

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    #14
    That's my question as well. I'm guessing that DTS passthrough works and DTA-MA passthrough makes the file unplayable.

    Unfortunately, doing DTS-MA passthrough only covers lossless audio for one of 3 options as there's no way to passthrough TrueHD and PCM. I could always just demux the HD audio and store the files that way for future proofing.

    I'd do some testing myself, but right now I don't have my audio system up. I'm building a new home and am parked up in a small rental for the next 9 months. In the new place, I'll have the full A/V system again. I'm trying to get all my media squared away in the meantime though, hence the questions.
     
  15. macrumors member

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    #15
    FYI, I tried an encode using DTS-MA passthrough in the third audio track. It plays fine for me on AppleTV and my new iPad.
     
  16. mic j, Apr 14, 2012
    Last edited: Apr 14, 2012

    macrumors 68020

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    #16
    Would you mind posting your exact file order and settings? I would like to try and reproduce what you're doing. I have tried it twice and each time the aTV 3 would not access the file.

    Thanks.

    Edit: I see you said the 3rd audio track and passthru. So I have no idea what the problem Dynaflash and myself are having.
     
  17. macrumors 68020

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    #17
    My test was standard dts pass thru on the third track. Tracks 1 and 2 were typical aac + ac3.

    I will test a bit more later tonight or tomorrow.
     
  18. macrumors 68020

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    #18
    I put DTS-MA passthru in the 3rd and DTS passthru in the 4th
     
  19. macrumors member

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    #19
    Has anyone been successful in getting DTS core passthrough to work from a DTS-MA source track? That doesn't seem to work for me. I can do DTS-MA passthrough from a DTS-MA track, but not DTS passthrough. I posted for support on the Handbrake forums as well, as I thought that would have worked.
     
  20. macrumors 68030

    nateo200

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    #20
    Yes. I've tried pretty much every combo in an mp4 container and I had Band of Brothers in .mp4's with the DTS core....with Handbrake you can now convert DTS-HD-MA, TrueHD or any other source to FLAC (although its limited to 16-bit) which you can easily open in Audacity and export as single .WAV/AIFF files (use AIFF since .WAV over 4GB requires 64bit wav which I don't feel like messing with) which you can then input into Compressor, DTS Master Audio Suite, or Dolby Media Encoder. Other wise you can export the entire file as L-PCM. If you use a PS3 (I don't but allot do) you can convert to 768kbps AAC which from a lossless source should sound AMAZING since 320kbps AAC is allot better transparent sounding than AC-3 or old school DTS. 6 channel AAC is useless for me since nothing but a PS3 or stand alone media player can decode it and pass it as multichannel PCM....
     
  21. macrumors 6502

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    #21
    Yes, used DTS passthrough. File plays fine in iTunes and iPad 2, ATV3 and iPhone 4.
     
  22. macrumors member

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    #22
    Dts pass through in handbrake

    The current HB help file, under surround sound, states unequivocally that at this time HB does NOT support DTS pass through. Goes on to say that DTS is great, but on a disc with DTS and AC3, the DTS is reduced to 768 and while thats adequate, the AC3 track will sound just as good....

    SO how are you guys passing through DTS on either a 2nd or third track??
     
  23. macrumors 68020

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    #23
    0.9.6 allows it. the wiki us outdated.

    Edit: presuming your are referencing https://trac.handbrake.fr/wiki/DTS
     
  24. macrumors member

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    #24
    I am using 9-6 and have been working on this a

    while. when HB is open, there is a help button up top and hitting that takes you to a HB user guide. In that guide, under surround sound, it has headings for 3 types of audio, DTS being one. When you hit that red link you find what I posted. The help file is not identified as Wiki.. I dont think it is.
    Always ready to hear new thoughts on this...
    Actually what I have started to do lately is use ffmpeg and 6 channel discrete for the AC track with the 5.1 AC track as the source. I match the bit rate to the MKV file, so most are 448, some 384... Of all the combinations I have tested, recorded down, endless partial encodes,, etc,, you know the drill.. this seems to give me the best overall sound. The receiver is not being pushed volume wise, and the info panel reports DOLBY - DIGITAL HDMI. The AC track averages around 480 mb in size with some movies going over 500 mb.
    By comparison AC pass thru sounds some what flat and using the DTS track either with pass through, or encoded with ffmpeg. This could be a limit of my receiver not liking the 768, but I dont think so.
     
  25. macrumors 68020

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    #25
    Trust me. It is. Here is specificially the link I put into the HB macgui and yes, its a wiki.

    https://trac.handbrake.fr/wiki/HandBrakeGuide
     

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