Opened 8 years ago

Closed 2 weeks ago

Last modified 13 days ago

#11184 closed Developer Task (Fixed)

Rewrite DVB profiles to filter unwanted streams instead of looking for expected streams

Reported by: stuartm Owned by: Klaas de Waal
Priority: minor Milestone: 31.0
Component: MythTV - Recording Version: Master Head
Severity: medium Keywords:
Cc: Ticket locked: no

Description

This setting appears to the opposite of what the help text implies. e.g. the TV only stream will looks for the expected streams (video/audio) instead of simply filtering out all the unwanted streams (mheg etc). If an expected stream is missing, e.g. video on a radio-only channel, then the recording will fail. See #10920

This understandably causes some confusion and it's more logical and useful to simply exclude the streams we don't want, e.g. data for "TV Only", data and video for "Audio Only"

Change History (6)

comment:1 Changed 8 years ago by J.Pilk@…

I don't know what the effect of this on dvb-t radio would be. Here's ffmpeg -i analysis of a BBC Radio 3 recording with 'Normal' encoder settings. When played it has an MHEG screen display that takes several seconds to appear. 0.25-fixes.

Mediainfo lists only the 0x4b2 stream.

Input #0, mpegts, from '1703_20121018125800.mpg':
Duration: 01:09:58.92, start: 43167.824967, bitrate: 1412 kb/s
Program 1
Stream #0:0[0x4b2](eng): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16, 192 kb/s
Stream #0:1[0x4ba]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:2[0x1ce9]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:3[0x1c21]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:4[0x1c22]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:5[0x1c23]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:6[0x1c24]: Unknown: none ([11][0][0][0] / 0x000B)
Stream #0:7[0x1c25]: Unknown: none ([11][0][0][0] / 0x000B)

comment:2 Changed 8 years ago by J.Pilk@…

For info; I usually process such recordings with mplayer -dumpaudio -dumpfile and keep the resulting .mp2 file. This plays in eg mythmusic but inherits none of the metadata, which it would be nice to have. ffmpeg -i from the above recording is:

Input #0, mp3, from '1703_20121018125800.mp2':

Duration: 01:09:58.92, start: 0.000000, bitrate: 192 kb/s

Stream #0:0: Audio: mp2, 48000 Hz, stereo, s16, 192 kb/s

comment:3 Changed 2 weeks ago by Stuart Auchterlonie

Milestone: unknownneeds_triage
Owner: changed from danielk to Klaas de Waal
Status: newassigned

Klaas, can you review and see if this is feasible?

comment:4 Changed 2 weeks ago by Klaas de Waal

I did not even know this option existed... However, it looks like the problem as described here has been solved already.

Configure recordings to use the MyGica?? T230 USB tuner which is a "DVB-T/S/C, ATSC or ISDB-T Tuner Card" device. Select "Hardware DVB Encoders" profile "Low Quality" and changed the "Recording Type" to "Audio Only".

Recording a TV program (audio plus video) with this profile then results in a file with only the audio; the video is filtered out. This is the expected result.

Select "Hardware DVB Encoders" profile "Low Quality" and changed the "Recording Type" to "TV Only". Recording a radio program (audio only) with this profile then results in a file with only audio. No error messages because of a missing video stream, as indicated in the ticket.

Therefore I think this ticket can be closed.

There are some other remarks to be made about the Recording Profile feature.

I think the best approach is to always record the complete program and at playback time decide which streams to use. I do not see any real advantage, other than a minimal space saving, of filtering out some of the streams when making the recording. The disadvantage is clearly that, when playing back, you might want the stream that has been filtered out.

There is one interesting feature and that is the "Record Full TS" option which is documented in the help text to generate an additional".ts.raw" file which then has the full contents of the transport stream. However, it does not record the complete transport stream but it does add the complete PSI information (NIT, SDT, PAT, PMT etc) of the transport stream to the recording. This is useful because it is easier to do than make a full MPTS recording, it is much smaller and it does have all the information needed for debugging.

It is possible to generate a new profile in addition to "Default", "Live TV", "High Quality" and "Low Quality". However, I could not find a way to select the new profile in the "Storage Options", first entry, when making a recording.

comment:5 Changed 2 weeks ago by Stuart Auchterlonie

Resolution: Fixed
Status: assignedclosed

Closing based on Klaas's feedback

comment:6 Changed 13 days ago by Stuart Auchterlonie

Milestone: needs_triage31.0
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