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)
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
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