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

Taylor Ralph taylor.ralph at gmail.com
Sat Dec 4 20:20:39 UTC 2010

On Sat, Dec 4, 2010 at 3:13 PM, Jerry Rubinow <jerrymr at gmail.com> wrote:
> 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?
> -Jerry

It would be much more helpful if you posted a log with the video in
question playing with the -v playback,timestamp options.


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