[mythtv-users] Channel scanner won't find a specific channel
David Parker
parker.david.a at gmail.com
Sat Feb 6 04:02:57 UTC 2016
Hello,
I've made a ~100 MB sample available here:
https://drive.google.com/file/d/0BypQdHvM5DGjeF9jT1NzcDVEbjA/view?usp=sharing
[1]
This is the first 54 seconds of the recording which I have been testing
with this whole time. This file is choppy when played through MythTV, but
plays fine everywhere else. It even plays just fine in the Google player
which shows in browser when you first click the link.
I've tried the other suggestions (thanks for those, guys!), and here are my
results:
1. Running "femon -H" shows the same information regardless of what channel
I am watching. It just says this:
status SCVYL | signal 92% | snr 0% | ber -1 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 92% | snr 0% | ber -1 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 92% | snr 0% | ber -1 | unc 0 | FE_HAS_LOCK
Note sure what the -1 BER value means, and Google wasn't much help. But
the other channels work fine and still had that value, so it seems like
it's ok (that could be a gross misjudgment on my part, though).
2. The original recording and the 100 MB sample I extracted both stutter
terribly in MythTV. But the version created using "mythtranscode -m" plays
perfectly. Any idea why?
Thanks John for the mythtranscode tip. This is a bit less of a
show-stopper now, since it looks like I can record from this channel and
then run a mythtranscode job to fix the video. I still don't know why this
particular channel causes such trouble, though, but only for MythTV.
Thanks!
Dave
[1] Note for future readers: not a permanent link.
On Fri, Feb 5, 2016 at 11:53 AM, John Pilkington <J.Pilk at tesco.net> wrote:
> On 05/02/16 16:08, David Parker wrote:
>
>> On Fri, Feb 5, 2016 at 9:33 AM, David Parker <parker.david.a at gmail.com
>> <mailto:parker.david.a at gmail.com>> wrote:
>>
>> On Fri, Feb 5, 2016 at 7:33 AM, John Pilkington <J.Pilk at tesco.net
>> <mailto:J.Pilk at tesco.net>> wrote:
>>
>> On 05/02/16 04:35, David Parker wrote:
>>
>> <snip>
>>
>> I haven't had a chance to try the lossless transcode yet,
>> but I did
>> verify that this is only a MythTV issue. I recorded a
>> program from this
>> troublesone channel, and it has consistently had choppy
>> audio and video
>> every time I've watched the recording in MythTV. I copied
>> the mpeg file
>> from the "recorded" directory to another PC with far worse
>> hardware and
>> an older version of Debian. The video played flawlessly in
>> Xine on the
>> other PC.
>>
>>
>> Have you looked at the frontend log, perhaps with -v playback?
>> There are other tools you could use to examine the file (vlc,
>> mediainfo) but it doesn't sound as if your problems are with
>> faulty or noisy capture.
>>
>> There are ways of filtering out unwanted streams; mythutil
>> --help shows several tools for mpeg-ts files (which I have never
>> tried) and I routinely use a script to do it - but it would be
>> better to get the recorder to do that rather than try to fix
>> things later. There are a few options in mythtvsetup.
>>
>> HP-mini had some good suggestions too, but I won't copy them here.
>>
>>
>> What's really got me scratching my head is the fact that
>> this one single
>> channel is choppy when I watch it live through MythTV, too.
>> So for some
>> reason, MythTV is having issues with the data coming from
>> the tuner for
>> this one particular channel. Same channel which MythTV
>> couldn't even
>> find until I told it where to look.
>>
>> The channel is crystal clear on the TV.
>>
>>
>> Thanks for the suggestions, guys. I'll give these a try. I want to
>> avoid troubleshooting this as an issue with the stream itself,
>> though. As I said before, if I take the mpeg recorded by MythTV and
>> play it in another player (such as Xine), it's fine. So this seems
>> to only be an issue with MythTV's playback of the recording, and
>> only seems to be with recordings from that particular channel. It's
>> very strange.
>>
>> I'll try some of these suggestions and post back my results.
>>
>> Thanks!
>>
>>
>> As a quick first test, I tried playing a few videos through MythTV with
>> "-v playback" set, as John suggested.
>>
>> For a problematic recording, the following lines were logged by
>> avformatdecorder.cpp which may be useful (timestamps and thread info
>> removed for brevity):
>>
>> CoreContext avformatdecoder.cpp:980 (InitByteContext) - AFD: Buffer
>> size: 32768 streamed 0 seekable 1
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #0, has
>> id 0x6f codec id MPEG2VIDEO, type Video, bitrate 0 at 0x308b360
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #1, has
>> id 0x70 codec id AC3, type Audio, bitrate 384000 at 0x30708e0
>> CoreContext avformatdecoder.cpp:2141 (ScanStreams) - AFD: codec AC3 has
>> 6 channels
>> CoreContext avformatdecoder.cpp:2198 (ScanStreams) - AFD: Looking for
>> decoder for AC3
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x3084b40, id(AC3) type(Audio)
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #2, has
>> id 0x71 codec id AC3, type Audio, bitrate 192000 at 0x3084fa0
>> CoreContext avformatdecoder.cpp:2141 (ScanStreams) - AFD: codec AC3 has
>> 2 channels
>> CoreContext avformatdecoder.cpp:2198 (ScanStreams) - AFD: Looking for
>> decoder for AC3
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x3095900, id(AC3) type(Audio)
>> CoreContext avformatdecoder.cpp:2340 (ScanStreams) - AFD: Trying to
>> select best video track
>> CoreContext avformatdecoder.cpp:2376 (ScanStreams) - AFD: Selected track
>> #0 (id 0x6f codec id MPEG2VIDEO, type Video, bitrate 500000 at 0x308b360)
>> CoreContext avformatdecoder.cpp:2511 (ScanStreams) - AFD: Using 0 CPUs
>> for decoding
>> CoreContext avformatdecoder.cpp:1556 (InitVideoCodec) - AFD:
>> InitVideoCodec() 0x308b640 id(MPEG2VIDEO) type (Video).
>> CoreContext avformatdecoder.cpp:1460 (normalized_fps) - AFD: Selected
>> FPS is 59.9401 (avg 59.9401 codec 59.9401 container 90000 estimated
>> 59.9401)
>> CoreContext avformatdecoder.cpp:1918 (UpdateATSCCaptionTracks) - AFD:
>> EIA-608 caption service #1 is in the Unknown language.
>> CoreContext avformatdecoder.cpp:2523 (ScanStreams) - AFD: Using ffmpeg
>> for video decoding
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x308b640, id(MPEG2VIDEO) type(Video)
>> CoreContext avformatdecoder.cpp:1359 (OpenFile) - AFD: Position map found
>> CoreContext avformatdecoder.cpp:1364 (OpenFile) - AFD: Successfully
>> opened decoder for file: "/mnt/data/recorded/1115_20160204170000.mpg".
>> novideo(0)
>>
>> Then the video began playing, choppy as always. The log was filled with
>> lines like this:
>>
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.2288
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 786432, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.50501
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 819200, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.45711
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 851968, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.1661
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 884736, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 917504, 65536) -> 65536, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 983040, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 1015808, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.25613
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1115_20160204170000.mpg):
>> safe_read(... at 1048576, 65536) -> 65536, took 0 ms (1000Mbps) avg 187 ms
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.34328
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>> CoreContext mythplayer.cpp:1967 (AVSync) - Player(0): Video is 3.15387
>> frames ahead of audio,
>> doubling video frame interval to slow down.
>>
>> Then I played a video recorded off a different HD channel, which plays
>> fine. The avformatdecoder.cpp messages for this file were as follows:
>>
>> CoreContext avformatdecoder.cpp:980 (InitByteContext) - AFD: Buffer
>> size: 32768 streamed 0 seekable 1
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #0, has
>> id 0x79 codec id MPEG2VIDEO, type Video, bitrate 0 at 0x33ed0a0
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #1, has
>> id 0x7a codec id AC3, type Audio, bitrate 384000 at 0x33deb60
>> CoreContext avformatdecoder.cpp:2141 (ScanStreams) - AFD: codec AC3 has
>> 2 channels
>> CoreContext avformatdecoder.cpp:2198 (ScanStreams) - AFD: Looking for
>> decoder for AC3
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x3589be0, id(AC3) type(Audio)
>> CoreContext avformatdecoder.cpp:2099 (ScanStreams) - AFD: Stream #2, has
>> id 0x7b codec id AC3, type Audio, bitrate 128000 at 0x35c1f20
>> CoreContext avformatdecoder.cpp:2141 (ScanStreams) - AFD: codec AC3 has
>> 2 channels
>> CoreContext avformatdecoder.cpp:2198 (ScanStreams) - AFD: Looking for
>> decoder for AC3
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x33ffe80, id(AC3) type(Audio)
>> CoreContext avformatdecoder.cpp:2340 (ScanStreams) - AFD: Trying to
>> select best video track
>> CoreContext avformatdecoder.cpp:2376 (ScanStreams) - AFD: Selected track
>> #0 (id 0x79 codec id MPEG2VIDEO, type Video, bitrate 500000 at 0x33ed0a0)
>> CoreContext avformatdecoder.cpp:2511 (ScanStreams) - AFD: Using 0 CPUs
>> for decoding
>> CoreContext avformatdecoder.cpp:1556 (InitVideoCodec) - AFD:
>> InitVideoCodec() 0x360c000 id(MPEG2VIDEO) type (Video).
>> CoreContext avformatdecoder.cpp:1460 (normalized_fps) - AFD: Selected
>> FPS is 29.97 (avg 29.97 codec 29.97 container 90000 estimated 29.97)
>> CoreContext avformatdecoder.cpp:1918 (UpdateATSCCaptionTracks) - AFD:
>> EIA-708 caption service #1 is in the English language.
>> CoreContext avformatdecoder.cpp:2523 (ScanStreams) - AFD: Using ffmpeg
>> for video decoding
>> CoreContext avformatdecoder.cpp:2632 (OpenAVCodec) - AFD: Opened codec
>> 0x360c000, id(MPEG2VIDEO) type(Video)
>> CoreContext avformatdecoder.cpp:1359 (OpenFile) - AFD: Position map found
>> CoreContext avformatdecoder.cpp:1364 (OpenFile) - AFD: Successfully
>> opened decoder for file: "/mnt/data/recorded/1241_20160204160000.mpg".
>> novideo(0)
>>
>> There were a handful of those "doubling video frame interval to slow
>> down" messages logged within the first second that the video was
>> playing, but after that, all of the messages while it played looked like
>> this:
>>
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1241_20160204160000.mpg):
>> safe_read(... at 3145728, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1241_20160204160000.mpg):
>> safe_read(... at 3178496, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1241_20160204160000.mpg):
>> safe_read(... at 3211264, 32768) -> 32768, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1241_20160204160000.mpg):
>> safe_read(... at 3244032, 98304) -> 98304, took 0 ms (1000Mbps) avg 187 ms
>> RingBuffer ringbuffer.cpp:1037 (run) -
>> RingBuf(/mnt/data/recorded/1241_20160204160000.mpg):
>> safe_read(... at 3342336, 65536) -> 65536, took 0 ms (1000Mbps) avg 187 ms
>>
>> I noticed that the AC3 audio bitrate of the choppy video is 192000,
>> while that of the stable video is 128000. I also noticed that the
>> selected framerate of the choppy video was ~60 FPS, whereas that of the
>> stable video was ~30 FPS. Still, it seems that 60 FPS and an audio
>> bitrate of 192000 should be handled easily by this PC (AMD Phenom II X3
>> 2.8 GHz, 4 GB RAM).
>>
>> Thanks!
>> Dave
>>
>
> Well, the ~60 Hz vs ~30 Hz video frame rate offers a plausible
> explanation; and both your samples seem to have prime audio rates of 384
> kbs, so I guess that's standard. I doubt that I can do much more now, but
> a sample would probably be of interest :-)
>
> Cheers,
>
> John
>
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://lists.mythtv.org/mailman/listinfo/mythtv-users
> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20160205/4d95ea33/attachment.html>
More information about the mythtv-users
mailing list