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

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Sun Nov 11 15:56:46 CET 2007


On 11/11/07 15:45, Reinhard Nissl wrote:
> Hi,
> 
> Klaus Schmidinger schrieb:
> 
>>>> 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
> 
> You're right. That's why it nolonger has the extension .pes ;-)
> 
>>> 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.
> 
> See attachment. This is what file says about my input file:
> 
> noSignal.png: PNG image data, 720 x 576, 8-bit/color RGB, non-interlaced
> 
>> 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?
> 
> Don't think so.

Looks like it is the file size.
I have now changed the line

  mpeg2enc -f 7 -T 90 -F 3 -np -a 2 -v 0 -o "$TMP2"

to

  mpeg2enc -f 7 -T 40 -F 3 -np -a 2 -v 0 -o "$TMP2"

so that the resulting file is about the same size as yours, and now
my images also are smooth. However, this most likely means that the
picture resolution is now reduced.

Maybe sending a large I-frame continuously causes trouble in the FF DVB cards.



Is there a way to generate a sequence of one (large) I-frame, followed
by some number of P-frames, which indicate that there is no change in
the image data? Like creating an MPEG sequence from a set of still
images, where all stills are the same.

Klaus



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