[mythtv] max channels on a stream

Michael T. Dean mtdean at thirdcontact.com
Sat Dec 17 13:09:22 EST 2005

Martin Ebourne wrote:

>On Sat, 17 Dec 2005 10:20:11 -0500, Daniel Kristjansson wrote:
>>MPEG-1 can handle one or two audio channels, MPEG-2 can handle 5.1
>>channels with the simple profile, and 48 audio channels with the advanced
>>profile. I would think it might be best to try to detect the limits of the
>>sound card, then find matching audio. Or, remix a multi-channel track to
>>the number of audio channels on the sound card we have, assuming 5.1 or
>>7.1 configuration when presented with 6 or 8 channel audio, resp..
>>DTS supports just 5.1 channels, and the 0.1 channel is low freq only.
>DTS disks with 6.1 discrete channels definitely exist. I don't think there
>are any with 7.1 yet (not sure even if that is possible?). This page lists
>some 6.1 titles and has a bit more info at the bottom:
That would be DTS-ES.

    - AC-3 (a.k.a. Dolby Digital): 5.1 (supports bitrates up to 
640Kb/sec, but ATSC limits the bitrate to 384Kb/sec and digital cable TV 
standards limit the bitrate to 448Kb/sec)
    - DTS (formerly Digital Theater Surround/Systems): 5.1
    - *Dolby Digital EX: 6.1 or 7.1 (using matrixed rear channels) - 
proprietary AC-3 format extension from Dolby (does not contain a 
discrete 6th channel, so not "true" 6.1/7.1)
    - *DTS-ES: 6.1 or 7.1(includes a discrete 6th channel)
    - *Dolby Digital Surround EX: 6.1 or 7.1 - proprietary AC-3 format 
extension from Dolby (includes discrete 6th channel)
    - Dolby TrueHD: 8 full-range channels (includes support for lossless 
    - Dolby Digital Plus: 13.1 (includes higher bitrates up to 6.144Mb/sec)
    - DTS HD (formerly DTS++): virtually unlimited number of surround 
channels that can be downmixed to 5.1- or 2-channel

* Although these support 7.1-channel audio systems, the 6th and 7th 
channels are identical (i.e. it's two "rear-center" speakers playing a 
mono signal).


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