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Thread: Video stuttering: messages about RingBuf, waiting for data

  1. #1
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    Video stuttering: messages about RingBuf, waiting for data

    I'm having playback issues for liveTV on a separated two frontend with one backend mythbuntu 12.04 system using MythTV 0.26-0 with latest update from PPA.

    Code:
    Dec  3 20:37:19 myth mythlogserver: mythbackend[2641]: I ProcessRequest ringbuffer.cpp:1098 (WaitForAvail) RingBuf(/mnt/mythtv/mythtv/livetv/2409_20121203193057.mpg): Waited 0.2 seconds for data #012#011#011#011to become available... 131072 < 360448
    Dec  3 20:37:23 myth mythlogserver: mythbackend[2641]: I ProcessRequest ringbuffer.cpp:1098 (WaitForAvail) RingBuf(/mnt/mythtv/mythtv/livetv/2027_20121203193426.mpg): Waited 0.2 seconds for data #012#011#011#011to become available... 129780 < 131072
    Dec  3 20:37:36 myth mythlogserver: mythbackend[2641]: I ProcessRequest ringbuffer.cpp:1098 (WaitForAvail) RingBuf(/mnt/mythtv/mythtv/livetv/2409_20121203193057.mpg): Waited 0.2 seconds for data #012#011#011#011to become available... 327680 < 360448
    Dec  3 20:37:36 myth mythlogserver: mythbackend[2641]: I ProcessRequest ringbuffer.cpp:1098 (WaitForAvail) RingBuf(/mnt/mythtv/mythtv/livetv/2409_20121203193057.mpg): Waited 0.2 seconds for data #012#011#011#011to become available... 65536 < 360448
    I have moved default storage group including liveTV-dir to a separate SSD with a xfs file system.
    When watching live HD-channels liveTV stutters when messages above are written to the log.

    I have read the other thread about ringbuf causing video buffers. It seems to be a different problem?

    Backend:
    MythTV Version0.26.0+fixes.20121203.b28041a-0ubuntu0mythbuntu2
    Motherboard: Gigabyte PH67-UD3-B3
    CPU: Intel(R) Core(TM) i3-2100T CPU @ 2.50GHz
    Harddrives: two Intel X25M SSD, one for OS, one for default storage
    2:0.26.0+fixes.20121203.b28041a-0ubuntu0mythbuntu2
    Memory: 8GB
    DVB-S: TBS 6984 - quad tuner card

    Frontend: Two Asrock nettop ION 3D 1.8 2GB/320GB harddrive using VDPAU
    Last edited by Erik-NA; December 5th, 2012 at 10:18 PM.

  2. #2
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    Re: Video stuttering: messages about RingBuf, waiting for data

    Does the stuttering continue if you pause for a few seconds and then resume? There was a bug at one stage where the playback was following the recording too closely and running out of data.

  3. #3
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    Re: Video stuttering: messages about RingBuf, waiting for data

    Yes, the stuttering continues if I pause for a few seconds and then resume.

    If I download a live recording from the livetv directory and watch it in VLC on Windows, the stuttering is visible in the recording.

    I shall make a test with mplayer to verify that the DBS S2 signal to MythTV is not the cause.

  4. #4
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    Re: Video stuttering: messages about RingBuf, waiting for data

    So it appears to be a recording issue, not a playback issue.

    Could be bad reception (check antenna and all cables), bad network between your tuner and your backend (if it is a network tuner), bad IO or backend otherwise swamped. What does iotop tell you?

  5. #5
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    Re: Video stuttering: messages about RingBuf, waiting for data

    I have a similar problem on my 12.04 system running the fixes .26 ppa. I can't use the frontends at the same time anymore to watch Live TV while the other is watching a recording. This worked fine before, but seems to have crept into an update sometime in the last month or so. They both stutter and buffer then live tv errors out with a ring buffer error, then the recording playback resumes.

    I have a dedicated backend, and the only thing I can think of is that maybe the ext4 partition were the recordings and live tv buffer is having an issue? When I rebuilt the system about 2 years I took the default option of using ext4 and not xfs.

  6. #6
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    Re: Video stuttering: messages about RingBuf, waiting for data

    Quote Originally Posted by nickrout View Post
    So it appears to be a recording issue, not a playback issue.

    Could be bad reception (check antenna and all cables), bad network between your tuner and your backend (if it is a network tuner), bad IO or backend otherwise swamped. What does iotop tell you?
    I have repositioned my PCI and PCIe cards to allow the DVB-card to have its own interrupt. I cannot see anything strange with iotop. The stuttering is still there, so reposition the DVB-card did not solved my problem.

    I am going to check the input signal from LNB, but due to bad weather conditions I have not done that yet.

    I am starting to believe that maybe this is an issue in the myth backend recording?
    Last edited by Erik-NA; December 5th, 2012 at 10:17 PM.

  7. #7
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    Re: Video stuttering: messages about RingBuf, waiting for data

    Quote Originally Posted by uteck View Post
    I have a similar problem on my 12.04 system running the fixes .26 ppa. I can't use the frontends at the same time anymore to watch Live TV while the other is watching a recording. This worked fine before, but seems to have crept into an update sometime in the last month or so. They both stutter and buffer then live tv errors out with a ring buffer error, then the recording playback resumes.

    I have a dedicated backend, and the only thing I can think of is that maybe the ext4 partition were the recordings and live tv buffer is having an issue? When I rebuilt the system about 2 years I took the default option of using ext4 and not xfs.
    What errors do you have in your mythtv-backend.log? Same as me as in the first post in this thread?

  8. #8
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    Re: Video stuttering: messages about RingBuf, waiting for data

    Now I have reinstalled the backend with other motherboard and a newer CPU.I have realigned my sat antenna, check all the cabling an so on. But it did not solved the problem. The video sometimes stutters, even if I download a LiveTv recording and watch it with VLC.

    My DVB-S2 card is a PCIe quad tuner card, TBS 6984

    HD channels are only affected, I have not seen any stutter on SD channels.
    Last edited by Erik-NA; December 12th, 2012 at 12:05 PM.

  9. #9
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    Re: Video stuttering: messages about RingBuf, waiting for data

    High - looking at your hardware configuration you seem to have most of your disc storage on the frontends. If this is correct the bandwidth on the network while recording could be the cause of the problem.
    Alternatively a quad tuner card has the potential to generate very high system loads. I remember seeing a driver update on the TBS website to sort out an interrupt problem. Have you downloaded and built the latest version.
    Best of luck.

  10. #10
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    Re: Video stuttering: messages about RingBuf, waiting for data

    The backend is equipped with a 3TB Raid 5 disc array. I have configured a 700MB XFS partition to be used as the standard storage group for the mythtv-backend.

    I have also changed motherboard to a Asus P8H77-V to get the TBS-card on an own interrupt. And I have also changed CPU to an Intel Core I5 3470S 2,9GHz.

    The TBS-card is installed with the latest TBS-drivers, currently v121119.

    I am also investigating if my cable signal is to low since I cannot get higher signallevel than 74% displayed in MythTvFrontend. But there are others reporting that they cannot get higher signal level than 74% using TBS-cards.

    I shall also rescan the channels, I notified during last scan that some HD channels got two neighboring SIDs (is it called SID? Or channel numbers?) which is a bit suspicious.
    Last edited by Erik-NA; December 13th, 2012 at 02:12 PM.

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