[mythtv-users] analog recordings won't play with some devices (long and confusing)

D. Hugh Redelmeier hugh at mimosa.com
Tue May 11 04:31:35 UTC 2010

I have two MythTV backends that record analog signals using Hauppauge
tuners and am having trouble playing the recordings with various
non-Myth devices.


- why can mplayer not play some of my recordings from MythTV 0.22
  while it can play recordings from MythTV 0.20?

- why can Linux-based XBMC not play my recordings with MythTV 0.22 but
  it can play recordings from MythTV 0.20?  Yet OSX-based XBMC can
  play them.

- why can WDTV not play any of my MythTV recordings (albeit with two
  different failure modes)?

Details (very long!):

Recording systems:

(1) an old MythTV 0.20 setup (32-bit system Fedora Core 5).
    Uses a PVR-250 and a few Adaptec VideOH! AVC 2410 cards (a lot
    like a PVR-150).
    Recording Profile: width 352, Height 480, CODEC MPEG-2,
    Stream Type MPEG-2 PS, Aspect Ratio 4:3,
    (video) Avg bitrate 2251, Max bitrate 3009,
    (audio) sampling rate 3200, type Layer 2, Bitrate 384Kb/s,
    SAP/bilingual main language, Volume (%) 90.

(2) a newer Mythbuntu with MythTV 0.22 (64-bit).
    Uses the analog sections of two Hauppauge HVR 1600 tuners.
    The driver for the tuners is from the hg repository since
    the one in Ubuntu's kernel isn't stable.

    (a) default recording profile.  Similar to (1) except
        width 480, Avg bitrate 4500, Max bitrate 6000,
        Sampling rate 4800.  I didn't choose this, it just happened.

    (b) recording profile adjusted to be closer to (1) but some
        divergence remains:
        Avg bitrate 2200, Max bitrate 3200, Sampling rate 4800
        (Sampling rate cannot be adjusted.)

Playback systems:

(i) Mythbuntu with MythTV 0.20 -- suitable for playing back recordings
    from (1).  Cannot play recordings from (2) since MythTV versions are
    required to match.  (Transport protocol: Myth)

(ii) Mythbuntu (2) can act as its own front end.  Cannot play
     recordings from (1) because the MythTV versions differ.
     (Transport protocol: Myth)

(iii) mplayer on a variety of Linux systems (transport protocol: http,
      NFS, or direct file-system access).

(iv) AppleTV (MacOSX) running XBMC (transport protocol: UPnP or Myth
     -- I'm not sure)

(v) Acer Revo (Atom + nVidia Ion) running XBMC under 64-bit Linux with
    nVidia proprietary X driver. (transport protocol: UPnP or Myth).
    (Similar results running XBMC on (2) with an nVidia proprietary

(vi) WD-TV live; firmware 1.02.21 and earlier (transport protocol: UPnP or SMB)


(i) works fine as a frontend for (1) but not (2) (version clash)

(ii) similarly works fine for (2) but not (1) (version clash)

(iii) has worked well for (1).  I've used Mythweb to give me a URL to
      feed mplayer.

      It did not work for (2a).  It always failed with the error
	Too many video packets in the buffer: (4096 in 7900000 bytes).

      Googling lead me to this thread
      which lead me to play with the recording profile, creating (2b).

      mplayer works with (2b).  I find this quite mysterious.

(iv) works well for both (1) and (2)

(v) works well for (1) but not (2)
    It seems odd that XBMC on OSX works but not on Linux.

    The failure mode is:

    - XBMC doesn't correctly know the length of the recording

    - playing fails part way through a recording.
      Sometimes quite early, sometimes as much as an hour in.
      Sometimes the failure is just a stop, sometimes a constant
      stuttered repeat happens.

(vi) fails for (1).  I described this in this thread:
     I still have no answers to those questions.

     Fails for (2) differently.  It starts to play, sound and picture,
     but after a few seconds the image freezes and the sound crackles
     and stops.

Other oddities:

- why does the WDTV think it can handle recordings from (2a) and (2b)
  but not (1)?

- why does the HVR-1600 analog section driver only allow a 48000 audio
  sample rate?  I think that the hardware is very similar to the
  PVR-150 that does allow various audio sample rates.

- mediainfo, applied to a recording from (1) and from (2b), shows no
  differences that look material.

Is there a tool to check standards conformance of a video recording?

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