How can I tell if a satellite audio stream is 5.1? (3 Viewers)

[Stéphane Lenclud]

That's too bad.

 

[mm1352000]

ah, found an explanation why it cannot work:
https://forum.team-mediaportal.com/t...v-in-the-tvplugin.127921/page-13#post-1109770

I would say that explanation is not very good, if it is valid at all. In the same way that TsWriter (and TV Server) could be modified to read that information, TsReader could also be modified to do the same without decoding the audio.

 

[Vasilich]

so that means it is possible to read that information from the stream somehow without actually decoding it?

 

[mm1352000]

so that means it is possible to read that information from the stream somehow without actually decoding it?

Yes, exactly... at least in some (most?) cases.

For example...

In DVB, the component_descriptor() (ETSI EN 300 468 section 6.2.8) there are stream_content and component_type fields which usually specify this information. For example:

• SC = 0x6 and CT = 0x5 means surround sound HE-AAC
• SC = 0x4 means AC-3 or E-AC-3; the MSB of CT indicates AC-3 or E-AC-3; the 3 LSB of CT indicate the channel config (eg. 3 = 2 channel surround encoded, 4 = multi-channel > 2 channels, 5 = multi-channel > 5.1 channels); refer to annex D section D1
• SC = 0x7 means DTS or DTS HD; the 3 LSB of CT indicate the channel config (eg. 4 = multi-channel > 2 channels); refer to annex G section G3.4

In the ATSC AC-3_audio_stream_descriptor() (ATSC A/52 annex A section A4.3) there is a num_channels field. According to A/65 this descriptor is mandatory in the PMT.
In the ATSC E-AC-3_descriptor() (ATSC A/52 annex G section G3.5) there is a number_of_channels field. According to A/65 this descriptor is mandatory in the PMT.

 

[Owlsroost]

My current dev versions of TsReader.ax do parse the actual audio stream to extract the audio channel count (so it can generate the mediatype information on the output pin correctly). It also logs the information (and detects changes to channel count during play).

In reality TV audio streams quite often change channel count during ad breaks and between programmes e.g. adverts are usually stereo and the movie might be 5.1

 

[Vasilich]

@regeszter should we also try to implement this? we can do 2 variables : AudioChannels - for pure channel count (e.g. for AC3 5.1 it should return 6), and AudioChannelsString - real description (e.g. Stereo, Mono, Dual Mono, Stereo surround, 5.1, 7.1 etc)

 

[Vasilich]

In reality TV audio streams quite often change channel count

will then AudioChannels variable value be changed? so i can see it in OSD when calling it during ads.

My current dev versions of TsReader.ax

Is this version far from release?

 

[regeszter]

@regeszter should we also try to implement this? we can do 2 variables : AudioChannels - for pure channel count (e.g. for AC3 5.1 it should return 6), and AudioChannelsString - real description (e.g. Stereo, Mono, Dual Mono, Stereo surround, 5.1, 7.1 etc)

Why not?

 

[mm1352000]

should we also try to implement this? we can do 2 variables : AudioChannels - for pure channel count (e.g. for AC3 5.1 it should return 6), and AudioChannelsString - real description (e.g. Stereo, Mono, Dual Mono, Stereo surround, 5.1, 7.1 etc)

Can I sneak in a request?
It would be cool to be able to show the "type" of audio stream. For example:

• receiver mix audio description for visually impaired
• broadcast mix audio description for visually impaired
  
• audio for the hard of hearing
• music and effects
  
• dialogue
• commentary
• emergency
• voice-over
• karaoke
• etc.

These details can be retrieved from the descriptors that I mentioned earlier.

 

[Vasilich]

if Owlsroost already did some parsing in its code, then i think it would be more effective to continue/extend his work in this direction.
@Owlsroost can we get your current code for TSReader?