ATSC3 issues with audio/video

WNYOTA · July 1, 2024, 5:49pm

I don’t think above is an Apple beta issue. It’s happening to me and I don’t have any beta OSs installed.

Your channel is a Sinclair channel. One of my Sinclair channels is having the same issue. This is an ATSC 3.0 implementation issue, not a beta issue.

Sinclair has been testing out using MMT instead of ROUTE-DASH with at least 6 stations across the country recently. Also, they have been testing Dolby Atmos instead of normal Dolby Surround 5.1.

My station, WUTV, has a technical info panel that looks essentially identical to yours, and it behaves the same way. It only happens with one channel out of the 5 on the WNYO lighthouse, WUTV. Also, I’ve noticed that the ADTH Box is unable to play it and the Zinwell ZAT-600B is only able to play video.

From what I have been finding out, I believe this issue is due to MMT being used instead of ROUTE-DASH, and due to Dolby Atmos AC4 being used instead of standard mono, stereo, or surround 5.1.

Also, the SiliconDust HDHomeRun app is able to play both the audio and video perfectly fine on that channel. I believe Channels will have to update their app to support this.

elvisimprsntr · July 1, 2024, 9:18pm

I get a slightly different outcome when using HDHR app

First attempt it will not decode video
Second attempt will decode video, but no audio
Third attempt will decode video and eventually start to decode audio.

Just seems to have difficultly detecting and decoding audio and video.

WNYOTA · July 2, 2024, 4:06pm

I can confirm the issue is due to the way the audio is being sent. The ATSC 3.0 version of WUTV is being sent with 10 channel audio (I can’t confirm whether it’s 5.1.4 or 7.1.2). My ADTH Box was behaving the same way as Channels (no audio, frozen picture, spinning wheel) until I installed a software update on the ADTH Box. It now plays the audio perfectly fine and identifies it as 10 channel audio. They’re also still using ROUTE-DASH, not MMT:

Channels will need to update their app to support Dolby Atmos. I think the audio may be 5.1.4 since it was mentioned in this article that Sinclair was a part of: https://tvnewscheck.com/tech/article/immersive-audio-still-a-work-in-progress-for-nextgen-tv/

speedingcheetah · July 2, 2024, 11:30pm

Channels supports Atoms just fine, at least for Local Media Library. I have played several movie rips recently that have Atmos audio, and the Display Stats shows it is outputting Atmos. Though, I do not have a Atmos speaker setup to confirm it is infact Atmos.
Though, i do not know if they are setup to support Atmos for TV live streaming though... I have never heard of even ATSC3.0 broadcasting in Atoms.

WNYOTA · July 2, 2024, 11:58pm

Yeah, some broadcasts are starting to. Channels will need support for live streams with Atmos.

tmm1 · July 3, 2024, 1:00am

Send a 60s recording from that station to support@getchannels.com

elvisimprsntr · July 3, 2024, 9:30am

Captured 60s of WPEC 112.1 in WPB. Email sent.

CAPTURE METHOD

curl "http://hdhomerun.local:5004/tuner0/v112.1?duration=60" -o wpec_atsc3.mpg

ENCODING

Used mediainfo app to read encoding. Looks like it is AC-4 5.1.4

General
ID                                       : 1 (0x1)
Complete name                            : /Users/Downloads/wpec_atsc3.mpg
Format                                   : MPEG-TS
File size                                : 33.9 MiB
Duration                                 : 59 s 809 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 749 kb/s
Frame rate                               : 59.940 FPS
Conformance errors                       : 2
 MPEG-TS                                 : Yes
  General compliance                     : File size 35505016 is less than expected size at least 35505116 (offset 0x21DC320)
 General compliance                      : Element size 184 is more than maximal permitted size 84 (offset 0x21DC324)
FileExtension_Invalid                    : ts m2t m2s m4t m4s tmf ts tp trp ty

Video
ID                                       : 49 (0x31)
Menu ID                                  : 3 (0x3)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L4.1@Main
HDR format                               : SL-HDR1, Version 1.0, Parameter-based, non-constant
Codec ID                                 : 36
Duration                                 : 59 s 793 ms
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
Mastering display color primaries        : BT.709
Mastering display luminance              : min: 0.0000 cd/m2, max: 1000 cd/m2

Audio #1
ID                                       : 50 (0x32)
Menu ID                                  : 3 (0x3)
Format                                   : AC-4
Format/Info                              : Audio Coding 4
Commercial name                          : Dolby AC-4
Format version                           : Version 2
Codec ID                                 : 6
Duration                                 : 59 s 859 ms
Channel(s)                               : 10 channels
Channel layout                           : L R C LFE Ls Rs Tfl Tfr Tbl Tbr
Sampling rate                            : 48.0 kHz
Frame rate                               : 29.970 (30000/1001) FPS (1601.6 SPF)
Compression mode                         : Lossy
Delay relative to video                  : 66 ms
Language                                 : English
I-Frame interval                         : 60 frames
Number of presentations                  : 1
NumberOfGroups                           : 1
Number of substreams                     : 1
Presentation #1                          : 5.1.4 Main (English)
 Presentation ID                         : 0
 Dolby Atmos                             : Yes
 Dialogue normalization                  : -24.00
 Language                                : English
 Loudness                                : Yes
  Integrated loudness (speech gated)     : -24.6 LKFS
  Integrated loudness (level gated)      : -24.4 LKFS
  Audio Loudness Standard                : ATSC A/85
  Realtime loudness corrected            : Yes
  Dialogue corrected                     : Yes
 Dynamic Range Control                   : Yes
 Downmix                                 : Yes
  LoRo center mix gain                   : -3.0 dB
  LoRo surround mix gain                 : -3.0 dB
  LtRt center mix gain                   : -3.0 dB
  LtRt surround mix gain                 : -3.0 dB
 Group #s                                : 1
Group #1                                 : Main
 Content classifier                      : Main
 Language                                : English
 Channel coded                           : Yes
 Number of substreams                    : 1
 Substream #s                            : 1
Substream #1                             : 5.1.4
 Channel mode                            : 5.1.4
 Channel layout                          : L R C LFE Ls Rs Tfl Tfr Tbl Tbr
 Dialogue enhancement                    : Yes
  Enabled                                : Yes
  Max gain                               : 9 dB
  Channel configuration                  : C

Audio #2
ID                                       : 51 (0x33)
Menu ID                                  : 3 (0x3)
Format                                   : AC-4
Format/Info                              : Audio Coding 4
Commercial name                          : Dolby AC-4
Format version                           : Version 2
Codec ID                                 : 6
Duration                                 : 59 s 960 ms
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 29.970 (30000/1001) FPS (1601.6 SPF)
Compression mode                         : Lossy
Language                                 : Spanish
NOK                                      : tools_metadata
I-Frame interval                         : 60 frames
Number of presentations                  : 1
NumberOfGroups                           : 1
Number of substreams                     : 1
Presentation #1                          : Stereo Main (Spanish)
 Presentation ID                         : 0
 Dialogue normalization                  : -24.00
 Language                                : Spanish
 Loudness                                : Yes
  Integrated loudness (speech gated)     : -25.2 LKFS
  Integrated loudness (level gated)      : -24.9 LKFS
  Audio Loudness Standard                : ATSC A/85
  Realtime loudness corrected            : Yes
  Dialogue corrected                     : Yes
 Dynamic Range Control                   : Yes
 Group #s                                : 1
Group #1                                 : Main
 Content classifier                      : Main
 Language                                : Spanish
 Channel coded                           : Yes
 Number of substreams                    : 1
 Substream #s                            : 1
Substream #1                             : Stereo
 Channel mode                            : Stereo
 Channel layout                          : L R
 Dialogue enhancement                    : Yes
  Enabled                                : Yes
  Max gain                               : 9 dB
  Channel configuration                  : L R

Menu
ID                                       : 48 (0x30)
Menu ID                                  : 3 (0x3)
Format                                   : HEVC / AC-4 /  / AC-4
Duration                                 : 59 s 776 ms
List                                     : 49 (0x31) (HEVC) / 50 (0x32) (AC-4, English) / 57 (0x39) () / 51 (0x33) (AC-4, Spanish)
Language                                 :  / English /  / Spanish

PLAYBACK

I could only get VLC to play video, no audio. Perhaps VLC can't decode 10 channel audio either.

Quicktime would not even play the video

Submitted bug reports for both VLC and QT

VIDEO

File to large to attach to email, so included public read only iCloud link.

wpec_atsc3.mpg

speedingcheetah · July 3, 2024, 2:15pm

Nothing to do with how many channels.. VLC, and nearly every other software player out there does not support AC4 audio.

You can compile your own version of ffmpeg that can support AC4, but it is tricky.
Though, i just use the Channels ffmpeg that comes with the Server install, to remux ATSC3.0 recordings to AC3 audio. (i made a thread on that while back)

elvisimprsntr · July 3, 2024, 2:36pm

Let me guess, Dolby proprietary licensing. Good job ATSC for adopting proprietary standards!

Dolby AC-4 is covered by patents and requires a license from Dolby Laboratories.[8] Dolby AC-4 has a consumer royalty rate of US$0.15 to US$1.20 depending on the type of device and volume of sales.[8] Dolby only charges for one technology per device, which means that Dolby AC-4 effectively costs nothing in devices that include existing Dolby technologies such as Dolby Digital Plus.[8] The professional royalty rate is up to US$50 for an eight channel transcoder.[8]

WNYOTA · July 4, 2024, 12:48pm

I just made a YouTube video showing this issue with Channels for HDHomeRun. Later on in the video shows how other ATSC 3.0 products were/are handling it.

Dolby Atmos Now Available With ATSC 3.0 Channels (Not Without Issues)

speedingcheetah · July 4, 2024, 2:34pm

That video plays fine for me in all players i have, no audio playback though, as expected.
As far as I found out, was over a year ago though, developers of VLC, and other software players for PC/Mac have no intentions to support AC4 audio anytime soon.

As far as the AC-4 audio on that specific station and recording file, I have to wonder if it is true Atmos and actually has 10 channels with proper audio in each track. That seems highly unlikely for a simple broadcast network station. There is zero chance that a simple local news broadcast is mastered with 10 audio channels. It most likely is fake 10 channel. (alike to how some cable channels i used to have would have fake 5.1 audio)

I can not seem to convert/transcode or even open up this AC-4 audio track to inspect the audio channels to see if there is actual audio in each channel. I just get errors trying to open. Maybe due to the software's i have tried not supporting such a format, or could be malformed audio track to begin with?? IDK. Either way, this just goes to show how wildly different the ATSC3.0 can be among markets.

Trying to convert this AC-4 to AC-3 like i do for my markets ATSC3.0 recordings, gives me this error fest: (it detects 12 channel audio?)

elvisimprsntr · July 4, 2024, 4:26pm

The HDHR app will play the video/audio of the ATSC3 station broadcasting AC-4 5.1.4 audio.

speedingcheetah · July 4, 2024, 4:59pm

That still doesn’t mean that it’s true multi channel audio. Unless you have a 10 channel audio set up to determine that whatever is being broadcast, actually has audio in each one of those channels

steved1990 · July 5, 2024, 1:31pm

I am having an audio issue on my Channels app on Apple TV. Unencrypted NextGen stations (only WGBH PBS in Boston) has a high pitched feedback noise. When I watch the same channel on the HD Homerun app on my apple tv, it sounds perfect. This has been going on for a while. Is there a fix for this?

WNYOTA · July 5, 2024, 9:43pm

I doubt it's natively 10 channel audio on most programming (if not all lol). It's similar to the HDR right now. The problem is, this station and a few others around the country are broadcasting this 10 channel audio, and the Channels app is having issues with it. I'd like to have audio when I play this channel!

WNYOTA · July 5, 2024, 9:45pm

I HAVE THE SAME ISSUE! It's really annoying! I thought this was an implementation issue at the broadcast end, then I started testing the ADTH Box, Zinwell ZAT-600B, and GTMedia HDTV Mate and none of them have that issue.

Channels has something implemented wrong with the AC4. The audio shouldn't sound like a tin can.

chDVRuser · July 6, 2024, 1:18am

Sparky · July 6, 2024, 11:07pm

Same issue using the newest HDHR box and channels (Apple TV).
The 3.0 channels looks like broken slow motion, tried switching audio driver and video driver.. no avail… but when I opened the HDHR app.. it worked fine audio and video…. Is there a setting I’m perhaps missing?

To add additional info… on appletv the issues exist
On iPad app (channels)it does not..aka works fine… could it be need 4k appletv for processing signal ?

Thanks

miceli · July 11, 2024, 7:45pm

This thread saved me the effort of gathering all the information and sending it to CDVR support. I have the same issue with WUTV described above but finally started to research it and ready to submit a ticket. I'm always running the latest beta on all my clients and the latest pre-release on my server so I'm running the latest everything.

Since the information was sent to @tmm1 I'm assuming he has all the information needed to hopefully resolve this issue. The no sound/freezing issue happens with wutv's ATSC3 signal with both Apple TV 4K and the Firestick for me. When trying to play wutv using the CDVR web browser I get:

2024/07/11 15:26:10.606211 [HLS] ffmpeg: ch129.1-dANY-ip192.168.1.3-1-h264-aac---9488-256-720-12-0--linear-false-false-0.01-0: Error while decoding stream #0:1: Invalid data found when processing input
2024/07/11 15:26:10.608240 [HLS] ffmpeg: ch129.1-dANY-ip192.168.1.3-1-h264-aac---9488-256-720-12-0--linear-false-false-0.01-0: [ac4 @ 0x8f84640] invalid channel mode: 12

in the CDVR logs. As stated above when viewing the station using HDHOMERUN software it plays video/audio without issue.

If I can supply any other information that may help just let me know. Here's hoping the developers can fix this issue soon.

tmm1 · July 11, 2024, 8:02pm

We need a 30s tuner capture from the station to be able to investigate. The only one provided above was for WPEC

Also note that we are not prioritizing ATSC3 development at this time until there is more clarity on the DRM issue.