Opened 12 years ago

Closed 12 years ago

Last modified 11 years ago

#5744 closed patch (wontfix)

Initial tuning to an analogue station fault

Reported by: anonymous Owned by: Janne Grunau
Priority: major Milestone: 0.21.1
Component: mythtv Version: 0.21-fixes
Severity: medium Keywords: analog analogue
Cc: Shane Shrybman Ticket locked: no


When initiating a tv session, initial tuning to an analogue channel fails. All that is produced is noise rather than a picture.

The fault has been located in: void TVRec::TuningNewRecorder?(MPEGStreamData *streamData) Line 4002 CloseChannel?()

CloseChannel? here is called with with the only file descriptor open on the video device. On certain tv cards at least, closing that single connection will initiate and a sleep state of the analogue frontend with loss of all previous tuning detail. In order to fix this, the CloseChannel? call is moved to a later point where it is known that the video device has been opened for reading elsewhere.

Testing results in success and inspection of file descriptors in use by the backend before and after shows no leakage.

Attachments (1)

TVRec_TuningNewRecorder_mythtv-0.21-fixes-18432.diff (665 bytes) - added by anonymous 12 years ago.

Download all attachments as: .zip

Change History (7)

Changed 12 years ago by anonymous

comment:1 Changed 12 years ago by Shane Shrybman

Cc: Shane Shrybman added
Status: newassigned

I have applied this patch and it works fine with my bttv (V4L2) and pvr250.

I think it also solves a problem I had with the bttv card seeing a second or two of static when first tuning livetv. It also may solve a problem where I only got a black screen on ~ 1/20 livetv startup attempts, I have not been able to reproduce that problem in ~40 attempts with the patch applied.

BTW: The #ifdef USING_V4L appears redundant, GetV4LChannel() has the USING_V4L check.

comment:2 Changed 12 years ago by Janne Grunau

Owner: changed from Isaac Richards to Janne Grunau
Status: assignedaccepted

comment:3 Changed 12 years ago by Janne Grunau

Status: acceptedinfoneeded

on trunk after [19250] it seems to have the different effect. I got a green screen on the first tuning attempt.

comment:4 Changed 12 years ago by danielk

Resolution: wontfix
Status: infoneededclosed

Info needed but not provided.

This looks like a workaround for broken V4L drivers, should be fixed upstream first, then we can add a workaround for the specific broken driver with version check. That way the hack can easily be removed when all major distros have been shipping non-broken drivers sufficiently long.

comment:5 Changed 12 years ago by patrick@…

I also have the problem described in this issue. Is there any other workaround or do I need to patch mythtv?

comment:6 Changed 11 years ago by patrick@…

I applied the patch to 0.22 and everything works fine with (HVR-4000)

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