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Some movies don't have audio, unless I...

508 Views 5 Replies 4 Participants Last post by scorrpio, Feb 21, 2014

ReyVGM

Discussion Starter · Feb 19, 2014

I tried googling this, but I have no idea what to search exactly because I don't know if it's the Home Theater or the TV. Hopefully someone will explain it to me.

I have a Panasonic Plasma VT60 and an Onkyo HT3500.

The Onkyo is connected to the TV through the ARC HDMI input. With this, the sound settings on the TV are greyed-out. The only option that is not, is "Digital audio out selection: Auto or PCM".

Now, here's the problem: I have a few movies on a hard drive, and some of them don't have any audio when I'm using the Onkyo (sound is fine when using the TV's speakers and on my computer too). I noticed that when I select "PCM" on the TV's sound options, I do get sound just fine through the Onkyo.

So my questions are, why is this happening? Is there a quality difference between "Auto" and "PCM"? Should I just leave it as PCM and listen to everything using that mode? Is PCM "inferior"? Is the movie I'm playing have some kind of audio codec/type/style that the Onkyo is not recognizing or something?

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Selden Ball

· #2 · Feb 19, 2014

Do you have the hard-drive and BD player plugged into the TV?

If so, that's the problem. Except for their internal audio sources (i.e. over-the-air and network stations) most TVs can only forward stereo audio from devices plugged into them to the ARC output. A few can forward multichannel Dolby Digital. A much smaller number can forward multichannel DTS.

In other words, plug the Blu-ray player into the receiver. If you can, plug the disk into the Blu-ray player. Then you should be able to get full multichannel sound from the disk and the player. You might have to reset the Blu-ray player to factory defaults. Some models will only output stereo after they've detected that they were plugged into a stereo TV. The reset clears this setting.

Does this help?

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ReyVGM

Discussion Starter · #3 · Feb 19, 2014

Thanks for the reply. I do not have anything connected to the TV or Receiver other than the Hard Drive (to the TV).

I understand that the TV doesn't send the 5.1 sound signal to the receiver, but it could have fooled me! I can hear distinct sounds coming from each speaker. You're telling me the receiver is "faking it" then?

So the reason why the movie (It's Avatar BTW) is not playing any sound it's because it's using real 5.1 dolby/DTS/etc? What's happening when I select "PCM" on the TV? Why do I get sound by doing that? And is that downgrading the sound?

I was just wondering if PCM was inferior or if that movie uses some kind of advanced audio codec or type not supported by the TV.

I mean, I have no problem by leaving that setting on "PCM" all the time (since all movies seem to sound fine), I'm just wondering if I'm going to miss some kind of audio detail on other movies if I do so.

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Selden Ball

· #4 · Feb 20, 2014

Quote:
Originally Posted by ReyVGM /t/1518757/some-movies-dont-have-audio-unless-i#post_24381286

Thanks for the reply. I do not have anything connected to the TV or Receiver other than the Hard Drive (to the TV).

If you want to be sure to get full surround-sound you need to invest in a Blu-ray player which you plug into the receiver. I suggest a Sony BDP S3100 (last year's model) or S3200 (this year's model) or an S5100 or S5200 if you want to watch 3D movies. Playing files from disk through the TV is going to be problematic, as you've found.

Quote:
I understand that the TV doesn't send the 5.1 sound signal to the receiver, but it could have fooled me! I can hear distinct sounds coming from each speaker. You're telling me the receiver is "faking it" then?

If you have selected either Dolby Prologic or DTS Neo:6 in the receiver, then often two-channel (stereo) expands to use more speakers. It depends on how the stereo soundtrack was generated. In particular, whether or not it was encoded to include matrixed surround sound.

Quote:
So the reason why the movie (It's Avatar BTW) is not playing any sound it's because it's using real 5.1 dolby/DTS/etc?

Right.

Quote:
What's happening when I select "PCM" on the TV? Why do I get sound by doing that? And is that downgrading the sound?

Something is converting the sound that's recorded in the file to two-channel PCM. It isn't obvious to me where that's happening. It could simply be that two channel PCM is included in the movie file.

Quote:
I was just wondering if PCM was inferior or if that movie uses some kind of advanced audio codec or type not supported by the TV.

If you're playing it from a file on the disk, I suspect it has a DTS soundtrack, which is not supported by the TV. PCM is not inferior in quality, just usually limited to stereo.

Quote:
I mean, I have no problem by leaving that setting on "PCM" all the time (since all movies seem to sound fine), I'm just wondering if I'm going to miss some kind of audio detail on other movies if I do so.

Possibly, which is why I suggest getting a Blu-ray player. The models I suggest support playing from an attached USB disk, from CD, DVD and BD discs, from network services like Netflix, Amazon and Vudu, and from files on a computer or file server on your home network running DLNA file-serving software. Of course, your TV does most of these things, too, except not Blu-ray discs.

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StamosD

· #5 · Feb 20, 2014

It sounds like you are trying to play a Ripped or Ripped/Compressed movie.

You simply may not have anything other than PCM stereo on the file.

Forcing the replay into PCM mode works.

Most players can pseudo create 5.1 from PCM.

Download this useful utility, it is open source from sourceforge:

http://mediaarea.net/en/MediaInfo

It will tell you exactly what Video and Audio Codecs exist in the file.

Stamos

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scorrpio

· #6 · Feb 21, 2014

Quote:
Originally Posted by ReyVGM /t/1518757/some-movies-dont-have-audio-unless-i#post_24381286

Thanks for the reply. I do not have anything connected to the TV or Receiver other than the Hard Drive (to the TV).

I understand that the TV doesn't send the 5.1 sound signal to the receiver, but it could have fooled me! I can hear distinct sounds coming from each speaker. You're telling me the receiver is "faking it" then?

So the reason why the movie (It's Avatar BTW) is not playing any sound it's because it's using real 5.1 dolby/DTS/etc? What's happening when I select "PCM" on the TV? Why do I get sound by doing that? And is that downgrading the sound?

I was just wondering if PCM was inferior or if that movie uses some kind of advanced audio codec or type not supported by the TV.

I mean, I have no problem by leaving that setting on "PCM" all the time (since all movies seem to sound fine), I'm just wondering if I'm going to miss some kind of audio detail on other movies if I do so.

The most important question is: In what format are these movies stored on the hard drive, and how were they placed there? Specifically, what is the format of the sound tracks on these movies? If you look at a typical DVD, it has a 5.1 track encoded in either Dolby Digital (DD) or DTS, potentially in several languages, but it will also usually have a two-channel track. Looking at a Blu-Ray, one may see an HD track (i.e. DTS-Master), a non-HD 5.1 track like DD (same as on a DVD), as well as a 2-channel track. Before the purists jump in: yes, it is noe exactly like this, but let's just say the formats are available. With ripped movies, especially those ripped from BluRay, you may get some sort of lossless FLAC track that's been recoded from a TrueHD track, or something like that. In any case, what does this mean?

When playing a movie, the player typically knows how it is connected and what formats the sound system supports. I.e. if connected via HDMI to a receiver that says it can handle HD stuff, TrueHD track is likely to be used. Now, your TV's ARC connection is exactly like optical - supporting all the same formats. Meaning you can send either regular DD or DTS, which is true encoded surround sound - or you can send PCM, which is simple, unencoded two channels. When your TV reads the movie off the hard drive, it sees the 2-channel track, and some other, encoded track that is the 'default one'. If TV is not connected to any external audio system, it 'knows' it only has 2 speakers, so it takes the 2-channel and plays it. But if TV is connected to external, it needs to choose a track. If set to 'Auto', it will try to pump the default track out to the receiver. If set to 'PCM', it will send the 2-channel one. If the default track is a plain DTS, your receiver will recognize and decode it. But if it's an HD codec or a FLAC, which are not supported via optical, your receiver will not know what to do with them.

Now, as I mentioned, PCM is just two channels of audio. However, your receiver is likely set by default to 'matrix' two channel sound into semblance of surround using Dolby Pro Logic or one of DTS Neo algorithms. With PCM, you will hear a kinda-sorta surround, not the true surround that you get by decoding a true discrete 5.1 channel DD or DTS bitstream.

What you could do is try to recode and repackage the movies on your hard drive to have DD5.1 tracks

Have a looks here
http://htcwiki.wikifoundry.com/page/How+to+keep+Dolby+Digital+5.1+audio+in+Blu-ray+movie%3F

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