Topic: Odd bitstreaming audio from OTA channels (Read 2333 times)

tzr916 · « **on:** November 01, 2022, 03:12:15 pm »

For a while now I've had zone switch setup so that Tv and Video use Bitstream audio, and Music does not. This has been working fine, until today. So, I just noticed that playing OTA Live tv, the audio INPUT format on my AVR said "Multi Channel" not "Dolby Digital"? However, if I play a Cable Card Live tv, or a recorded tv show (Cable Card or OTA) it says "Dolby Digital", like it always has.

I'm pretty sure that playing OTA Live tv has always said "Dolby Digital". Guessing this started when I installed MC v30 a few weeks ago. See screenshots of MC audio path info:

tzr916 · « **Reply #1 on:** November 03, 2022, 10:24:44 am »

Confirmed v29.0.85 plays OTA Live tv channels correctly, bitstream shows as Dolby Digital on AVR.

While MC v30 OTA Live tv is Multi Channel, but recorded shows from OTA channels playback as bitstream/Dolby Digital.

Yaobing · « **Reply #2 on:** November 03, 2022, 09:37:27 pm »

What result do you get if you play a DMS channel?

tzr916 · « **Reply #3 on:** November 04, 2022, 08:51:35 am »

DMS OTA channel plays correctly - MC bitstream output and shows as Dolby Digital on AVR.
So it's only BDA OTA that has the issue.

Yaobing · « **Reply #4 on:** November 04, 2022, 09:26:20 am »

Interesting. That is different from what I get. My old DAC does not handle AC3 streaming, so what I get may not be typical. If I turn on AC3 bitstreaming, this is what I get:

Playing a cable channel (CableCARD) with HDHomeRun Prime, I get silence and MC's audio path info says "Not using JRiver audio engine". This is the case when playback is done in DirectShow.

Playing an OTA bda channel, with HDHomeRun Flex 4k, I do get sound, with MC converting from AC3 to 2 channel. This is the case when tuning is done with DirectShow (bda), but playback is done without DirectShow.

Playing a DMS channel, using HDHomeRun Flex 4k, I get the same behavior as in bda channel. This is the case when playback does not use DirectShow.

So I thought the difference is whether we use DirectShow for playback. But your case seems to suggest differently.

Yaobing · « **Reply #5 on:** November 04, 2022, 09:44:29 am »

I just tried MC29. Its behavior is indeed different from MC30, but in a way that I would have expected.

Playing a bda channel, and playing a CableCARD channel have the same behavior, as both are using DiectShow. I get silence because my DAC does not handle it.

Playing all DMS channels, either cable or OTA, I do get sound, but the Audio path still says "Not using JRiver audio engine". That is a little surprising too.

The main difference is still whether we use DirectShow or not.

tzr916 · « **Reply #6 on:** November 04, 2022, 09:55:14 am »

I'm use BDA for cable card and OTA. Only OTA audio is affected:
MC29 OTA audio path INPUT Bitstreaming from source AC3 [no changes] OUTPUT Bitstreaming WASAPI
vs
MC30 OTA audio path INPUT 48kHz 32bit 6ch from source AC3 [no changes] OUPUT 48kHz 24bit padded 6ch WASAPI

Yaobing · « **Reply #7 on:** November 04, 2022, 12:19:34 pm »

I asked Hendrik about it. He said bitstreaming is supported only in DirectShow.

That explains what you observe. The OTA channels are now (in MC30) played using JR Video Engine, instead of DirectShow.

CableCARD playback is still in DirectShow. All DMS channels are played in non-DirectShow.

tzr916 · « **Reply #8 on:** November 04, 2022, 06:44:44 pm »

If I decided to change my OTA from BDA to DMS, is there currently a working Server~Client tuner setup method for DMS? Would I enable DMS tuners on all machines, or only the Server?

Yaobing · « **Reply #9 on:** November 04, 2022, 09:06:42 pm »

Quote from: tzr916 on November 04, 2022, 06:44:44 pm

If I decided to change my OTA from BDA to DMS, is there currently a working Server~Client tuner setup method for DMS? Would I enable DMS tuners on all machines, or only the Server?

Currently no. I will be working on it later. I will also make the new time-shifting for bda devices optional.

The new time-shifting vs. the old:

PRO: It allows a Mac/Linux client to play live TV with the bda tuner installed on a Windows OS running MC server. I started the new time-shifting method as a way of accommodating ATSC 3.0 channels. It turns out, there is a big issue in tuning to such channels within the framework of bda. Therefore the original goal may not be achieved, not soon anyway.

CON: Not supporting bitstreaming. Not keeping old channel data in the same time-shifting session if you switch channel during time-shifting. Recording can only be done in TS format, not in JTV format.

tzr916 · « **Reply #10 on:** November 05, 2022, 08:52:31 am »

Yes, I saw your posts over at the SD Dev Forum, quite the conundrum

I may try DMS on the Server to get bitstreaming back on my main tv room with AVR. I already have separate guides for Server vs Clients, where OTA is exposed on the Server and the comcast version of those channels are exposed on Clients. It's not going to be a fun process re-creating 75 ota recording rules (many of which are not currently on air, in the guide) and channel names/numbers/logos.

tzr916 · « **Reply #11 on:** November 06, 2022, 12:56:14 pm »

Quote from: tzr916 on November 04, 2022, 08:51:35 am

DMS OTA channel plays correctly - MC bitstream output..

How come when I copy and pasted a URL into MC to play the channel and it comes out bitstream? Such as
http://192.168.1.xx:5004/auto/v3.1
http://192.168.1.xx:5004/auto/v6.1

Quote from: Yaobing on November 04, 2022, 12:19:34 pm

I asked Hendrik about it. He said bitstreaming is supported only in DirectShow.

That explains what you observe. The OTA channels are now (in MC30) played using JR Video Engine, instead of DirectShow.

CableCARD playback is still in DirectShow. All DMS channels are played in non-DirectShow.

I have just finished setting up OTA DMS with guide info, and when I play OTA DMS channels from the guide I do NOT get bitstream. Getting the same as OTA BDA:
-audio path INPUT 48kHz 32bit 6ch from source AC3 [no changes] OUPUT 48kHz 24bit padded 6ch WASAPI

So getting bitstream when copy/paste the DMS channel URL into MC... but not when actually using the guide to play the same DMS channel ?

Yaobing · « **Reply #12 on:** November 07, 2022, 08:32:58 am »

When you play an URL directly, you have the option of playing it in DirectShow or not. MC defaults to DirectShow. That is why you do get bitstreaming in that case. When I implemented DMS channels, I had Mac and Linux on my mind so I implemented it without DirectShow.

Yaobing · « **Reply #13 on:** November 07, 2022, 08:45:56 am »

I am sorry, I wasn't even thinking when you said bitstreaming worked in DMS last week. I should have made it clear about it so you would not have wasted your time setting up the DMS channels.

After I implement making the new time-shifting for bda devices optional (soon), you can choose to play them in legacy time-shifting, i.e. DirectShow player engine, for all your non-ATSC3 channels.

tzr916 · « **Reply #14 on:** November 07, 2022, 08:55:41 am »

No problem, I did not change any of my record rules, just setup OTA DMS in the guide for testing.

I'm confused about the upcoming optional legacy direct show mode. Will that capable of bitstreaming for OTA? Or is bitstreaming for OTA completely gone for good?

Yaobing · « **Reply #15 on:** November 07, 2022, 09:08:32 am »

The legacy time-shifting means the mode used in MC29 and earlier. So it will support bitstreaming for OTA (bda) and OpenCABLE tuners.

tzr916 · « **Reply #16 on:** November 15, 2022, 08:02:12 pm »

Quote

30.0.31 (11/11/2022)
NEW: Added a TV option to choose whether to use the new transport stream time-shifting or legacy (program stream) time-shifting for bda tuners.

Thank you, this is working, I changed to legacy and have bitstreaming again... Unfortunately I am getting audio glitches every 4-6 seconds on certain OTA channels:
-only happens on LIVE tv
-only certain OTA channels, repeatable
-not present in MC v29, checked all OTA channels
-not audio drop outs, more like overlapping/garbled/glitching
-not present when playing back finished recordings of the affected OTA channels
-tried many variations of settings of audio device buffering and pre-buffering

Yaobing · « **Reply #17 on:** November 16, 2022, 10:38:05 am »

Hmm, more puzzles!

The option should have just brought back the old method. Let me do some digging and see if there are some spill over of the new method.

Yaobing · « **Reply #18 on:** November 17, 2022, 09:01:23 am »

I carefully looked over my code and could not find anything obvious. I can't reproduce the behavior either (but since I have completely different set of channels, that does not mean too much).

On the other hand, I have seen some audio issues but they are completely opposite to your cases. I get them from cable channels (such as CNNHD and AMCHD) instead of OTA (bda) channels. AND I get stutters when playing the channels using the new time-shifting method, not legacy method.

tzr916 · « **Reply #19 on:** November 18, 2022, 02:48:59 pm »

Seems like my OTA bda bitstream problem disappeared after installing v30.0.33

Yaobing · « **Reply #20 on:** November 19, 2022, 05:18:01 pm »

OK, let's hope it will stay disappeared

The issue of audio stuttering with the new time-shifting and DMS was fixed by Hendrik in a new build, which should be out in a few days.

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Author Topic: Odd bitstreaming audio from OTA channels (Read 2333 times)