[Live-devel] Motion JPEG header reconstruction bug

[Massimo Corà]

Hi all,

first of all thanks for coding LiveMedia which is a great piece of software.
I am trying to stream a .jpg file read from disk. I used, as I
understood from the mailing-list archive, a subclass of JPEGVideoSource
and a file JPEGStreamer which contains main(), MyJPEGVideoSource,
JPEGVideoRTPSink, rtsp server etc..
On the other side JPEGReceiver with JPEGVideoRTPSource, FileSink,
RTCPInstance.

Now the problems I encountered: first of all, FileSink doesn't write
anything to the output file with a calling like
FileSink::createNew(*env, "jpeg_received.jpg", 60000);
To have some data written I must set the file to stdout and then from
cmd line call: jpeg_receiver.exe >> output_file.jpg

Secondly I noticed that the reconstructed header from rtp packets [the
output_file.jpg] has some problems: after the 623 bytes of jpeg
header-length [and so just after 0x3F 0x00] there are *always* 4 bytes
CD CD CD CD before jpeg image-data starts. Perhaps this is caused by a
wrong use of buffers?!

Thirdly some other bytes inside jpeg header are not like the input image
from disk. But I still have to look at their meaning... Anyway it seems
independent from qFactor().

I attached the input.jpg and the output.jpg. Looking at them in an
hexadecimal editor can point out what I just have said.


Regards,

Massimo Cora'




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