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Test Cricket - plays BBC2 recording but not BBC4
linux at thehobsons
Aug 17, 2020, 3:36 AM
Post #1 of 5 (543 views)
Permalink
Can anyone shed any light on this ?
When I sit down to watch the Test Match highlights on BBC4 (7pm), I get a blank screen then a message about waiting too long for video to buffer. When I watch the same program recorded later on BBC2, it works just fine.

The one thing that comes to mind is that the BBC4 recording has a 5 minute pre-roll which starts before the channel is on air, while on the later BBC2 recording the pre-roll will be the end of a previous program. If this is the problem, is there a setting I'm missing as version 0.24.1 I used to run handled this - not very well, but it managed it.

Mediainfo suggests both are the same MPEG streams. If I download the ts file, VLC player plays it fine - it has the "We'll be on air at 7" card for a while then switches to video.


If I ask for verbose playback logging I get :

CoreContext tv_play.cpp:5943 (StartPlayer) - TV::StartPlayer(): Created player.
CoreContext tv_play.cpp:2576 (HandleStateChange) - TV::HandleStateChange(): Changing from None to WatchingRecording
Decoder avformatdecoder.cpp:1023 (HandleStreamChange) - AFD: streams_changed 0x55b44c0b0ac0 -- stream count 2
Decoder avformatdecoder.cpp:810 (SeekReset) - AFD: SeekReset(0, 0, do flush, do discard)
Decoder avformatdecoder.cpp:840 (SeekReset) - AFD: SeekReset() flushing
Decoder videoout_xv.cpp:1356 (DiscardFrames) - VideoOutputXv: DiscardFrames(1)
Decoder videobuffers.cpp:633 (DiscardFrames) - VideoBuffers::DiscardFrames(1): AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
Decoder videobuffers.cpp:694 (DiscardFrames) - VideoBuffers::DiscardFrames(1): AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP -- done
Decoder videoout_xv.cpp:1362 (DiscardFrames) - VideoOutputXv: DiscardFrames() 3: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP -- done()
Decoder avformatdecoder.cpp:2182 (ScanStreams) - AFD: Stream #0, has id 0x1c2b codec id DSMCC_B, type Data, bitrate 0 at 0x7f0134013f80
Decoder avformatdecoder.cpp:2245 (ScanStreams) - AFD: data codec (Data)
Decoder avformatdecoder.cpp:2182 (ScanStreams) - AFD: Stream #1, has id 0x1c21 codec id DSMCC_B, type Data, bitrate 0 at 0x7f0134016140
Decoder avformatdecoder.cpp:2245 (ScanStreams) - AFD: data codec (Data)
Decoder avformatdecoder.cpp:2443 (ScanStreams) - AFD: Trying to select best video track
Decoder avformatdecoder.cpp:2463 (ScanStreams) - AFD: No video track found/selected.
Decoder mythplayer.cpp:1800 (SetFrameInterval) - Player(0): SetFrameInterval ps:1 scan:3
Decoder videodisplayprofile.cpp:575 (LoadBestPreferences) - VDP: LoadBestPreferences(640x480, 25.000, mpeg2video)
Decoder videodisplayprofile.cpp:589 (LoadBestPreferences) - VDP: LoadBestPreferences Result prio:2, w:, h:, fps:, codecs:, decoder:ffmpeg, renderer:xv-blit, deint:gr
Decoder videoout_xv.cpp:253 (InputChanged) - VideoOutputXv: InputChanged(640,480,1.33333) 'MPEG2'->'MPEG2'
Decoder mythplayer.cpp:673 (detectInterlace) - Player(0): detectInterlace(Ignore Scan, Interlaced Scan, 25, 480) ->Interlaced Scan
CoreContext tv_play.cpp:2682 (HandleStateChange) - TV::HandleStateChange(): Main UI disabled.
CoreContext tv_play.cpp:432 (StartTV) - TV::StartTV(): Entering main playback loop.
CoreContext mythplayer.cpp:814 (SetScanType) - Player(0): Enabled Video Output based deinterlacing
CoreContext mythplayer.cpp:2469 (SetBuffering) - Player(0): Waiting for video buffers...
CoreContext mythplayer.cpp:2536 (PrebufferEnoughFrames) - Player(0): Waited 114ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
CoreContext mythplayer.cpp:2536 (PrebufferEnoughFrames) - Player(0): Waited 230ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP

<loads more lines like this, culminating in :>

CoreContext mythplayer.cpp:2532 (PrebufferEnoughFrames) - Player(0): Waited 29964ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
CoreContext mythplayer.cpp:2582 (PrebufferEnoughFrames) - Player(0): Waited too long for decoder to fill video buffers. Exiting..
CoreContext tv_play.cpp:2319 (HandleStateChange) - TV::HandleStateChange(): Attempting to change from WatchingRecording to None


MythTV Version : v30.0
MythTV Branch :
Network Protocol : 91
Library API : 30.20181231-1
QT Version : 5.7.1



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Re: Test Cricket - plays BBC2 recording but not BBC4 [ In reply to ]
johnpilk222 at gmail
Aug 17, 2020, 4:04 AM
Post #2 of 5 (543 views)
Permalink
On 17/08/2020 11:36, Simon Hobson wrote:
> Can anyone shed any light on this ?
> When I sit down to watch the Test Match highlights on BBC4 (7pm), I get a blank screen then a message about waiting too long for video to buffer. When I watch the same program recorded later on BBC2, it works just fine.
>
> The one thing that comes to mind is that the BBC4 recording has a 5 minute pre-roll which starts before the channel is on air, while on the later BBC2 recording the pre-roll will be the end of a previous program. If this is the problem, is there a setting I'm missing as version 0.24.1 I used to run handled this - not very well, but it managed it.
>
> Mediainfo suggests both are the same MPEG streams. If I download the ts file, VLC player plays it fine - it has the "We'll be on air at 7" card for a while then switches to video.
>
>
> If I ask for verbose playback logging I get :
>
> CoreContext tv_play.cpp:5943 (StartPlayer) - TV::StartPlayer(): Created player.
> CoreContext tv_play.cpp:2576 (HandleStateChange) - TV::HandleStateChange(): Changing from None to WatchingRecording
> Decoder avformatdecoder.cpp:1023 (HandleStreamChange) - AFD: streams_changed 0x55b44c0b0ac0 -- stream count 2
> Decoder avformatdecoder.cpp:810 (SeekReset) - AFD: SeekReset(0, 0, do flush, do discard)
> Decoder avformatdecoder.cpp:840 (SeekReset) - AFD: SeekReset() flushing
> Decoder videoout_xv.cpp:1356 (DiscardFrames) - VideoOutputXv: DiscardFrames(1)
> Decoder videobuffers.cpp:633 (DiscardFrames) - VideoBuffers::DiscardFrames(1): AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
> Decoder videobuffers.cpp:694 (DiscardFrames) - VideoBuffers::DiscardFrames(1): AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP -- done
> Decoder videoout_xv.cpp:1362 (DiscardFrames) - VideoOutputXv: DiscardFrames() 3: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP -- done()
> Decoder avformatdecoder.cpp:2182 (ScanStreams) - AFD: Stream #0, has id 0x1c2b codec id DSMCC_B, type Data, bitrate 0 at 0x7f0134013f80
> Decoder avformatdecoder.cpp:2245 (ScanStreams) - AFD: data codec (Data)
> Decoder avformatdecoder.cpp:2182 (ScanStreams) - AFD: Stream #1, has id 0x1c21 codec id DSMCC_B, type Data, bitrate 0 at 0x7f0134016140
> Decoder avformatdecoder.cpp:2245 (ScanStreams) - AFD: data codec (Data)
> Decoder avformatdecoder.cpp:2443 (ScanStreams) - AFD: Trying to select best video track
> Decoder avformatdecoder.cpp:2463 (ScanStreams) - AFD: No video track found/selected.
> Decoder mythplayer.cpp:1800 (SetFrameInterval) - Player(0): SetFrameInterval ps:1 scan:3
> Decoder videodisplayprofile.cpp:575 (LoadBestPreferences) - VDP: LoadBestPreferences(640x480, 25.000, mpeg2video)
> Decoder videodisplayprofile.cpp:589 (LoadBestPreferences) - VDP: LoadBestPreferences Result prio:2, w:, h:, fps:, codecs:, decoder:ffmpeg, renderer:xv-blit, deint:gr
> Decoder videoout_xv.cpp:253 (InputChanged) - VideoOutputXv: InputChanged(640,480,1.33333) 'MPEG2'->'MPEG2'
> Decoder mythplayer.cpp:673 (detectInterlace) - Player(0): detectInterlace(Ignore Scan, Interlaced Scan, 25, 480) ->Interlaced Scan
> CoreContext tv_play.cpp:2682 (HandleStateChange) - TV::HandleStateChange(): Main UI disabled.
> CoreContext tv_play.cpp:432 (StartTV) - TV::StartTV(): Entering main playback loop.
> CoreContext mythplayer.cpp:814 (SetScanType) - Player(0): Enabled Video Output based deinterlacing
> CoreContext mythplayer.cpp:2469 (SetBuffering) - Player(0): Waiting for video buffers...
> CoreContext mythplayer.cpp:2536 (PrebufferEnoughFrames) - Player(0): Waited 114ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
> CoreContext mythplayer.cpp:2536 (PrebufferEnoughFrames) - Player(0): Waited 230ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
>
> <loads more lines like this, culminating in :>
>
> CoreContext mythplayer.cpp:2532 (PrebufferEnoughFrames) - Player(0): Waited 29964ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP
> CoreContext mythplayer.cpp:2582 (PrebufferEnoughFrames) - Player(0): Waited too long for decoder to fill video buffers. Exiting..
> CoreContext tv_play.cpp:2319 (HandleStateChange) - TV::HandleStateChange(): Attempting to change from WatchingRecording to None
>
>
> MythTV Version : v30.0
> MythTV Branch :
> Network Protocol : 91
> Library API : 30.20181231-1
> QT Version : 5.7.1
>

BBC FOUR services start at 7 pm. I get good recordings with a 1-minute
pre-roll. With a 2-minute pre-roll the audio output graph in the
editor shows non-audio data, and for more than 2-minutes playback fails.

It's been like this 'forever'. I think dependence on MythTV version
arises because the mythffmpeg stream analysis has taken samples at
different places. Sometimes ffmpeg has worked when mythffmpeg has
failed, or vv.

I used to find that recordings from the kids' CBeebies channel that
recorded beyond the 7 pm changeover also failed to display properly.

If you want to keep a recording that is affected by this, try dropping
the first few MB.

https://code.mythtv.org/trac/ticket/13557#comment:13

John P


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Re: Test Cricket - plays BBC2 recording but not BBC4 [ In reply to ]
philledwards at gmail
Aug 17, 2020, 1:30 PM
Post #3 of 5 (539 views)
Permalink
On Mon., 17 Aug. 2020, 8:38 pm Simon Hobson, <linux@thehobsons.co.uk> wrote:

> Can anyone shed any light on this ?
> When I sit down to watch the Test Match highlights on BBC4 (7pm), I get a
> blank screen
>

That's because there's been no cricket due to rain and bad light!

>
Re: Test Cricket - plays BBC2 recording but not BBC4 [ In reply to ]
mythtv at mythqml
Aug 18, 2020, 4:04 AM
Post #4 of 5 (534 views)
Permalink
On 17/08/2020 11:36, Simon Hobson wrote:

> Can anyone shed any light on this ?
> When I sit down to watch the Test Match highlights on BBC4 (7pm), I get a blank screen then a message about waiting too long for video to buffer. When I watch the same program recorded later on BBC2, it works just fine.
>
> The one thing that comes to mind is that the BBC4 recording has a 5 minute pre-roll which starts before the channel is on air, while on the later BBC2 recording the pre-roll will be the end of a previous program. If this is the problem, is there a setting I'm missing as version 0.24.1 I used to run handled this - not very well, but it managed it.
>
> Mediainfo suggests both are the same MPEG streams. If I download the ts file, VLC player plays it fine - it has the "We'll be on air at 7" card for a while then switches to video.
>

BBC4 is a part time channel that starts broadcasting a minute or two
before 7PM. Before then there is an interactive TV place holder screen.
If you try to start recording BBC4 before it actually starts
broadcasting them MythTV gets confused and you get a bad recording. If
you start recording after it starts broadcasting then all should be OK.
Your 5 minute pre-roll is to long for this channel so change the
recording rule to start at recording at 7PM or no more than one minute
early and hopefully all should be good.


Paul H.

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Re: Test Cricket - plays BBC2 recording but not BBC4 [ In reply to ]
linux at thehobsons
Aug 18, 2020, 1:47 PM
Post #5 of 5 (525 views)
Permalink
Paul Harrison <mythtv@mythqml.net> wrote:
>

> BBC4 is a part time channel that starts broadcasting a minute or two before 7PM. Before then there is an interactive TV place holder screen. If you try to start recording BBC4 before it actually starts broadcasting them MythTV gets confused and you get a bad recording.

Except that it used to work when I was using 0.24.1 Before I upgraded, I just had to skip forward and when it got to where the program stream started it would start playing.
That's why I wonder if there might be a playback setting (decoder profile ?) I should be fiddling with to fix it ? Frontends are Intel NUC i3 with all defaults other than selecting the right audio output.

> If you start recording after it starts broadcasting then all should be OK. Your 5 minute pre-roll is to long for this channel so change the recording rule to start at recording at 7PM or no more than one minute early and hopefully all should be good.

Actually, the BBC have made the problem moot for the time being - it's moved to a single showing on BBC2 at 7pm now. I guess the snooker has finished.

Simon

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