[mythtv-users] How to improve 720p playback (1080i ok)?

Jerry Rubinow jerrymr at gmail.com
Sat Dec 4 20:13:22 UTC 2010

On Fri, Dec 3, 2010 at 8:45 AM, Jerry Rubinow <jerrymr at gmail.com> wrote:

> On Fri, Dec 3, 2010 at 2:28 AM, Raymond Wagner <raymond at wagnerrp.com>wrote:
>> On 12/3/2010 00:34, Jerry Rubinow wrote:
>>> With more investigation, I've found mpeg 480p, 720p and 1080i all play
>>> back ok.  It is H264 720p which does not.  Any ideas what to look into?
>> 720p60 means these are HDPVR recordings? What bitrate do you have it set
>> to?
> Yes.  The mpeg recordings are all HDHomerun, and the H264 720p60 is from
> the HDPVR.  It's set to whatever the default is - I've never changed it.
>  I'll try changing the bitrate and see what happens.  I do observe though
> that the CPU hovers in the low 30 percent range when playing back.  So I
> don't understand the reason for the pauses, if it's caused by too high a
> bitrate.

I lowered the bitrate down to 2000 in the profile and recorded a show, but
it still has the same problem.

To reiterate, 720p H264 recordings from the HDPVR exhibit pauses during
playback.  The log shows that frames are repeatedy being dropped because the
audio is ahead of the video.  I have no problem with 720p or 1080i mpeg
files from the HDHomeRun.  Playback is under mythfrontend compiled on a
Window box with ION video.  CPU usage during playback is low (around the low
30s percent).   Lower than with the mpeg playback.

I tried forcing the NVideo vsync setting off, didn't help.  Tried different
recording bitrates, as mentioned, didn't help.  Playback is configured to
use Direct3D / ffmpeg.

Can someone fill in any details about how mpeg decode differs from H264
decode in myth?

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