[mythtv-users] mp4 videos smearing at high than 3x FF

[Michael T. Dean]

On 09/12/2012 03:33 AM, Ian Evans wrote:
> On Sun, Sep 2, 2012 at 11:51 PM, Ian Evans<wrote:
>> On Sun, Sep 2, 2012 at 4:58 AM, Ian Evans wrote:
>>> I transcode a few SD shows to mp4 using a handbrake user job in .25.
>>>
>>> In the last few days I've noticed that if I fast forward at more than
>>> 3x, the video starts to "smear". Crystal clear at 3x.
>> Just a follow-up I played one of the files in VLC at is max of 4x and
>> it was clear. In Myth at 5x, the frames clump together like a smudged
>> oil painting.
>>
>> Again, this only happens with mp4 files. I can play an untranscoded
>> mpg file at 100x+.
>>
> Wow, this problem is just driving me a little nuts. Has anyone here
> seen anything like it? Here's the handbrakecli command used to
> transcode the recordings:
>
> /usr/bin/HandBrakeCLI -i $MYTHDIR/$MPGFILE -o $newname -e x264 -q 20.0
> -l 480 -a 1,2,3,4 -E faac -B 160 -R Auto -f mp4 --detelecine --decomb
> -m -x b-adapt=2:rc-lookahead=50
>
> Any idea what could cause Mythtv to act like this on these files?

IIRC, we play back at up to 3x by decoding faster, and above 3x, we just 
skip around in the video, so it sounds like your key frames are too far 
apart, so you're getting smearing when we skip.

Mike