[mythtv-users] Recording no longer watchable--transcoding issue?

Thu Jan 2 01:53:10 UTC 2020

Happy New Year to all!

Main problem: Yesterday, I was able to watch a movie recorded over the air
in the US (HDHomeRun, Myth 30).
Today, when I try to watch the same recording, it plays super-slowly and
the sound is mostly a loud hiss.

I'm quite sure I inadvertently triggered a transcoding yesterday, and
pretty sure the result is in a nuv container.  My guess is I'm experiencing
https://code.mythtv.org/trac/ticket/13459, although the reports there
mention only white noise.  I think I'm also hearing the audio track, but
slowed down beyond intelligibility.

I tried the maximum increase in playback speed available through the GUI,
2x, but it was still way too slow.

Is there a way to find out what I did--by which I mainly mean what specific
format the transcode was into--and to undo it?

The previous speculation is based on the following facts:

The myth backend log shows
2019-12-31 23:37:22.680885 I [7328/23423] Transcode_8671 jobqueue.cpp:2052
(DoTranscodeThread) - JobQueue: Transcode Starting for "Bonnie and Clyde":
Autodetect (2.7 GB)
That's the show I was watching, and around the time I stopped watching it.
And later:
2019-12-31 23:43:04.824798 I [7328/23423] Transcode_8671 jobqueue.cpp:2149
(DoTranscodeThread) - JobQueue: Transcode Finished: "Bonnie and Clyde":
Autodetect (6.6 GB)

There is a log for the transcoding session, but it is not obvious to me
what it thought it was transcoding to.  I hope the answer is in the
following section:
2019-12-31 23:37:23.350834 N [23425/23425] CoreContext main.cpp:556 (main)
- Transcoding from /srv/media10/media10-barley/20203_20191102235800.ts to
/srv/media10/media10-barley/20203_20191102235800.ts.tmp
2019-12-31 23:37:23.424713 I [23425/23425] CoreContext
avformatdecoder.cpp:2223 (ScanStreams) - AFD: codec AC3 has 2 channels
2019-12-31 23:37:23.424880 I [23425/23425] CoreContext
avformatdecoder.cpp:2772 (OpenAVCodec) - AFD: Opened codec 0x56004f9453c0,
id(AC3) type(Audio)
2019-12-31 23:37:23.426178 I [23425/23425] CoreContext
avformatdecoder.cpp:2670 (ScanStreams) - AFD: Using ffmpeg for video
decoding
2019-12-31 23:37:23.426335 I [23425/23425] CoreContext
avformatdecoder.cpp:2772 (OpenAVCodec) - AFD: Opened codec 0x56004f9644c0,
id(MPEG2VIDEO) type(Video)
2019-12-31 23:37:23.426369 N [23425/23425] CoreContext audioplayer.cpp:166
(ReinitAudio) - AudioPlayer: Enabling Audio
2019-12-31 23:37:23.447824 N [23425/23425] CoreContext transcode.cpp:120
(GetProfile) - Transcode: Looking for autodetect profile: Autodetect from
480i
2019-12-31 23:37:23.468413 N [23425/23425] CoreContext transcode.cpp:145
(GetProfile) - Transcode: Using autodetect profile: MPEG2
2019-12-31 23:37:23.483107 N [23425/23425] CoreContext transcode.cpp:817
(TranscodeFile) - Forcing Recorder option 'videocodec' to ''
2019-12-31 23:37:23.483127 E [23425/23425] CoreContext
recorders/recorderbase.cpp:211 (SetOption) - RecBase[NULL](): SetOption():
Unknown int option: videocodec: 0
2019-12-31 23:37:23.491402 I [23425/23425] CoreContext transcode.cpp:1084
(TranscodeFile) - Copying Audio while transcoding Video
2019-12-31 23:37:23.493041 I [23425/23436] VideoDecodeBuffer
mythcodeccontext.cpp:322 (InitDeinterlaceFilter) - MythCodecContext:
Disabled hardware decoder based deinterlacer.
2019-12-31 23:37:23.495820 E [23425/23425] CoreContext
mythsystemevent.cpp:345 (SendMythSystemRecEvent) - MythSystemEventHandler:
SendMythSystemRecEvent() called with empty RecordingInfo
2019-12-31 23:37:23.581490 I [23425/23438] SendMessage
mythcorecontext.cpp:451 (ConnectCommandSocket) -
MythCoreContext::ConnectCommandSocket(): Connecting to backend server:
192.168.1.10:6543 (try 1 of 1)
2019-12-31 23:37:23.581974 I [23425/23438] SendMessage
mythcorecontext.cpp:1677 (CheckProtoVersion) -
MythCoreContext::CheckProtoVersion(): Using protocol version 91 BuzzOff
2019-12-31 23:42:58.013340 E [23425/23436] VideoDecodeBuffer
avformatdecoder.cpp:5313 (GetFrame) - decoding error End of file
(-541478725)
2019-12-31 23:42:58.282608 N [23425/23425] CoreContext main.cpp:707 (main)
- Transcoding /srv/media10/media10-barley/20203_20191102235800.ts done
The specific codecs mentioned look as if they are about the source, not the
destination.
The show did have commercials marked in it.

I have also looked for documentation on transcoding, but what I've found is
pretty thin: some general discussion of transcoding, but nothing that lets
me figure out the default behavior, or how to accomplish it through the GUI.

Other symptoms are that there are no entries in the recordedseek table for
the program, that the recordedfile entry shows a container of NUV and file
size around 3G, while the recorded entry shows a file size of around 7G.
Here's the recordedfile entry:
| basename                | filesize   | width | height | fps    | aspect
| audio_sample_rate | audio_channels | audio_codec | video_codec | comment
| hostname | storagegroup | id   | recordedid | container | total_bitrate |
video_avg_bitrate | video_max_bitrate | audio_avg_bitrate |
audio_max_bitrate |
+-------------------------+------------+-------+--------+--------+----------+-------------------+----------------+-------------+-------------+---------+----------+--------------+------+------------+-----------+---------------+-------------------+-------------------+-------------------+-------------------+
| 20203_20191102235800.ts | 2903640072 |   720 |    480 | 29.970 | 1.777778
|                 0 |              0 | AC3         | MPEG2VIDEO  |
| barley   | Default      | 3489 |       3656 | NUV       |             0 |
                0 |                 0 |                 0 |
0 |
+-------------------------+------------+-------+--------+--------+----------+-------------------+----------------+-------------+-------------+---------+----------+--------------+------+------------+-----------+---------------+-------------------+-------------------+-------------------+-------------------+

I mostly think the file is in NUV format because of this entry and the
symptom similarity with the bug mentioned above.  However, that theory
means the recordedfile entry reflects the post-transcoded file.  But it
shows a file size of 3G, which the general log suggests was the size of the
file before transcoding, not after.

Here's what I get for the file right now:
ross at barley:/srv/media10/media10-barley$ file 20203_20191102235800.ts
20203_20191102235800.ts: MythTV NuppelVideo v0.07
(720x480),progressive,aspect:1.78,fps:29.97
ross at barley:/srv/media10/media10-barley$ ls -l 20203_20191102235800.ts
-rw-r--r-- 1 mythtv mythtv 7080326127 Dec 31 23:42 20203_20191102235800.ts

mediainfo doesn't report anything useful.

Thanks for any help.
Ross
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