Hi Gernot,
Am 19.11.2011 20:04, schrieb Gernot Ziegler:
> Hej Christian,
>
> sorry for disappointing you, but AFAIK, JPEG has different DCT
> coefficients, and thus you can't recode JPG frames into MPEG1.
>
> Regarding missing DHT segements, I don't know more than:
> You could try inserting the DHT segment from an encoded JPEG into the
> "broken" frames arriving from the stream? Or does the DHT segment
> differ for every frame? But that is the only "hack" I could think of
> (without getting deeper into the subject, I left it 10 years ago)
The DHT segment is constant. So it would be possible to insert some non
changing data into the broken frames. The question here is: Where to
insert? I really have no idea and so far found nothing about the
internal structure of jpeg images.
Regards
Christian
>
> Sorry to be of so little help,
> Gernot
>
>> Dear all,
>>
>> It might be that my question is a bit out of topic but I think you guys
>> might be able to help.
>>
>> You maybe know that a couple of modern webcams output some kind of
>> motion JPG image. The Logitech C905 webcam does so. The data is a
>> jpg-image without DHT segment. With the help of google I managed to
>> patch libjpeg to be able to decode these crippled jpg-images. The code
>> can be found here
>>
>> http://svn.openrobotino.org/common/trunk/lib/rec/cv_lt/jpeg_dec.cpp
>>
>> Still it would be nice to take the webcam's output and stream it
>> directly to a web browser. But because of the missing DHT segment
>> browsers are not able to decode the data. My work around right now is to
>> decode the data with my patched libjpeg and encode again as real jpg.
>> This works but puts my embedded platform to almost 100% cpu load.
>>
>> The question is if there is a way to insert the missing DHT segment to
>> the mjpg data without the need of decoding/encoding the image. Or is
>> there a simple way to make a mpg1 stream from these mjpg single images
>> coming from the webcam?
>>
>> Any help is highly appreciated
>> Regards
>> Christian
>>
>> --
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>
> Servus,
> Gernot
>
> GPU. 3D Vision. Europe. Future. Now.
> Drop by: www.mpi-sb.mpg.de/~gziegler - www.geofront.eu
>
>
> ------------------------------------------------------------------------------
> All the data continuously generated in your IT infrastructure
> contains a definitive record of customers, application performance,
> security threats, fraudulent activity, and more. Splunk takes this
> data and makes sense of it. IT sense. And common sense.
> http://p.sf.net/sfu/splunk-novd2d
>
>
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--
___________________________________________
REC GmbH
Dr. Christian Verbeek
Robert-Koch-Str. 2, 82152 Planegg
Tel: +49 89 85689672
Fax: +49 89 85902327
Mobile: +49 160 7056589
e-mail: verb...@servicerobotics.eu
Geschäftsführer: Dr. Christian Verbeek
Registergericht: AG München (HRB 154463)
____________________________________________
------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure
contains a definitive record of customers, application performance,
security threats, fraudulent activity, and more. Splunk takes this
data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
_______________________________________________
Mjpeg-users mailing list
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