[vdr] How to convert a JPEG image to an I-frame?

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Sun Nov 11 15:35:55 CET 2007


On 11/11/07 15:30, Klaus Schmidinger wrote:
> On 11/11/07 15:20, Reinhard Nissl wrote:
>> Hi,
>>
>> Klaus Schmidinger schrieb:
>>
>>> When I display a picture generated with this script through a call
>>> to DeviceStillPicture(), the display looks very nice for a short while,
>>> and after that slanted lines get jagged. It appears as if the two
>>> interlaced half-pictures are first sent in turn, and finally only
>>> one of them is displayed continuously.
>>>
>>> Calling DeviceStillPicture() repeatedly in a loop results in the
>>> display jumping between "nice" and "jagged".
>>>
>>> So I thought about sending the picture file to the device through
>>> cPlayer::PlayPes() in a continuous loop. For that purpose I have
>>> added a call to 'mplex' to the script, as can be seen in the attachment.
>>>
>>> When I display such a still file on a FF DVB card by calling cPlayer::PlayPes()
>>> in a continuous loop, the image on the tv screen looks like it is
>>> displaying both interlaced half-pictures in turn, but it is "jumpy" (as if
>>> the time between displaying the two half pictures is too long).
>>>
>>>
>>> Does anybody have an idea how this could be improved, so that
>>> I get a smooth display, with slanted lines not jagged (just as if
>>> a still picture was shown in a normal movie)?
>> How does the attached PES file look like? In vdr-xine, I send it just
>> once and it looks OK in xine.
>>
>> When it looks ok, I'll have to search for the commands which created it ;-)
>>
>> I think, I had specified an option to create progressive frames.
> 
> After running your file through
> 
>   mplex -f 7 -o test.mpg noSignal.mpg
> 
> and displaying test.mpg trough cPlayer::PlayPes() I get a pefectly
> smooth display.
> 
> Would be great if you could find the commands that created this one.

One more thing: the 'file' command reports

  MPEG sequence, v2, MP at ML interlaced Y'CbCr 4:2:0 video, 4CIF PAL, 4:3, 25 fps

on a file created with the posted script (before the mplex call),
while for your noSignal.mpg it reports

  MPEG sequence, v2, MP at ML interlaced Y'CbCr 4:2:0 video, CCIR/ITU PAL 625, 4:3, 25 fps

Maybe this indicates where the problem might be?

Klaus



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