[mythtv-users] v30 and DVB-T2 part-time channels - recordings without audio/video hanging mythfrontend

[John Pilkington]

re-sending to list

On 28/07/2019 23:29, Mark Cooke wrote:
> Hi All,
> 
> I finally managed to get my system updated from v28 (Ubuntu 16.04) to 
> v30 (Ubuntu 18.04).
> 
> I am using a self-compiled front end on OSX 10.13 (quite an involved 
> process but thanks to everyone posting top tips to the forum and list).
> 
> * Started with 
> https://github.com/warpme/mythv-osx-build-script/blob/master/osx-packager-qtsdk.pl 
> 
> * Updated to freetype 2.10.0
> * Updated to QT 5.11.3
> * Used MacPorts for python and freetype issue
> * Used the SDK workaround for Quicktime framework missing from 
> https://github.com/warpme/mythv-osx-build-script
> 
> 
> 
> It was mostly plain sailing with using MythTV 30 itself, so thank you 
> devs for the hard work!
> 
> 
> I have come across one issue that appears to be due to the UK habit of 
> having channels that broadcast 24x7 but only contain audio/video streams 
> for some of the time.
> 
> 
> The example I have most recently was from today.
> 
> BBC FOUR HD starts broadcasting at 7pm, and I had a recording setup for 
> the broadcast starting at 7pm.  With a system-wide 'start recording 
> early' configured, the TS file started to be saved from 6.50pm.
> 
> 
> Trying to play this recording jams up the frontend with a black screen 
> saying 'Please Wait'.  I can't escape, jump forward or backward or bring 
> up the menu when this happens.
> 
> Eventually (5+ minutes later) it drops back to the Watch Recording 
> screen with an error 'Video frame buffering failed too many times'.
> 
> 
> Outside of MythFrontend, the TS file will play (eventually) in VLC, with 
> the first video frame being ~ 650 MB into the file.
> 
> 
> So Myth appears to hiccup with TS files without audio/video, and I don't 
> know how to nicely fix this, other than avoid it happening by looking 
> carefully at recording rules.
> 
> 
> Anyone want this particular TS file to look further?  I have an 80MB 
> chunk that covers the period just before the start of broadcast, and the 
> 700MB snip that Myth was struggling with.
> 
> 
> mediainfo on the long lead in doesn't detect the video/audio stream but 
> there is a menu stream present, so the recording isn't completely absent:
> 
> General
> ID                                       : 45056 (0xB000)
> Complete name                            : snip.ts
> Format                                   : MPEG-TS
> File size                                : 700 MiB
> 
> Menu
> ID                                       : 1004 (0x3EC)
> Menu ID                                  : 1 (0x1)
> List                                     : 206 (0xCE) ()
> 
> 
> On the short extract, it is short enough that mediainfo reaches the 
> start of the audio/video:
> 
> General
> ID                                       : 45056 (0xB000)
> Complete name                            : snip2.ts
> Format                                   : MPEG-TS
> File size                                : 80.0 MiB
> Duration                                 : 1 s 260 ms
> Overall bit rate mode                    : Variable
> Overall bit rate                         : 2 731 kb/s
> 
> Video
> ID                                       : 201 (0xC9)
> Menu ID                                  : 1 (0x1)
> Format                                   : AVC
> Format/Info                              : Advanced Video Codec
> Format profile                           : High at L4
> Format settings                          : CABAC / 4 Ref Frames
> Format settings, CABAC                   : Yes
> Format settings, ReFrames                : 4 frames
> Codec ID                                 : 27
> Duration                                 : 680 ms
> Width                                    : 1 920 pixels
> Height                                   : 1 080 pixels
> Display aspect ratio                     : 16:9
> Frame rate                               : 25.000 FPS
> Standard                                 : Component
> Color space                              : YUV
> Chroma subsampling                       : 4:2:0
> Bit depth                                : 8 bits
> Scan type                                : Progressive
> Color range                              : Limited
> Color primaries                          : BT.709
> Transfer characteristics                 : BT.709
> Matrix coefficients                      : BT.709
> 
> Audio
> ID                                       : 202 (0xCA)
> Menu ID                                  : 1 (0x1)
> Format                                   : AAC
> Format/Info                              : Advanced Audio Codec
> Format profile                           : LC
> Muxing mode                              : LATM
> Codec ID                                 : 17-2
> Duration                                 : 1 s 260 ms
> Bit rate mode                            : Variable
> Channel(s)                               : 2 channels
> Channel positions                        : Front: L R
> Sampling rate                            : 48.0 kHz
> Frame rate                               : 46.875 FPS (1024 SPF)
> Compression mode                         : Lossy
> Language                                 : English
> 
> Text
> ID                                       : 203 (0xCB)
> Menu ID                                  : 1 (0x1)
> Format                                   : DVB Subtitle
> Codec ID                                 : 6
> Language                                 : English
> 
> Menu
> ID                                       : 1004 (0x3EC)
> Menu ID                                  : 1 (0x1)
> Duration                                 : 1 s 260 ms
> List                                     : 206 (0xCE) () / 201 (0xC9) 
> (AVC) / 202 (0xCA) (AAC, English) / 203 (0xCB) (DVB Subtitle, English)
> Language                                 :  /  / English / English
> 
> 
> Cheers,
> 
> Mark

It appears that my local DVB-T2 muxes are currently off-air, perhaps for 
G5 preparations; but if I have interactive TV enabled

Frontend Setup > Video > Playback OSD > Enable interactive TV

and try

Menu > Watch this channel

for BBC FOUR I get, after a few seconds, a screen saying it's off-air 
until 7.00 pm and suggesting use of iPlayer.

Without the interactive setting it shows a black screen, until Escaped.

One-off start-time adjustments can be done via the Edit menu of the 
'Upcoming recordings' screen.

John P