I'm dealing with Onvif too and I need to extend JPEGVideoSource, call it
JPEGVideoSourceEx. How to make the MediaSubsession create a JPEGVideoSourceEx
class instead of a JPEGVideoSource.
Thank you,
Renato MAURO
----- Original Message -----
From: Cristiano Belloni
To: LIVE555 Streaming Media - development & use
Sent: Wednesday, October 27, 2010 9:51 AM
Subject: Re: [Live-devel] JPEGVideoRTPSink and Restart markers
Il 27/10/2010 02:39, Ross Finlayson ha scritto:
I'm trying to create a rtsp server to stream MJPEG images.
Ugh. JPEG is a *terrible* codec for video streaming.
I agree, but *everyone* requests JPEG as an entry point. Onvif, for example,
requests MJPEG/RTP streaming as a MUST IMPLEMENT.
I have implemented a new TestJPEGFileServerMediaSubsession that creates
a TestJPEGVideoRTPSink.
In TestJPEGVideoRTPSink::doSpecialFrameHandling I'm adding the
quantization tables of the image into the header using setSpecialHeaderBytes
Note that the existing "JPEGVideoRTPSink" code already does this. You
should not have to reinvent the wheel here.
This is working fine using some JPEG images, but fails with others.
I'm testing one image that has the marker 0xFF, 0xDD ( Define Restart
Interval) and I think I have to do something else seeing this comment in the
code
// Note: We assume that there are no 'restart markers'
So, what should I do with images containing restart markers and
macroblocks?
The JPEG transmitting code ("JPEGVideoSource" and "JPEGVideoRTPSink")
currently don't support "Restart Marker Headers" (see RFC 2435, section 3.1.7).
You will need to update the (definition and implementation) of these two
classes to support them.
I did something similar, Francisco. In a nutshell, you've got to extend
JPEGVideoSource and look for DRI markers like this:
//Look for the DRI marker
for (unsigned i = 0; i < JPEGHeaderSize; ++i) {
if (fBuffer[i] == 0xFF) {
if (fBuffer[i+1] == 0xDD) { // DRI
if ((fBuffer[i+2] != 0) || (fBuffer[i+3] != 4)) {
envir() << "Wrong DRI marker!\n";
continue;
}
else {
fRestartInterval = (fBuffer[i+4] << 8) + fBuffer[i+5];
printf ("DRI restart Interval found @ %d is %d\n", i,
fRestartInterval);
break;
}
}
}
}
Then, extend JPEGVideoRTPSink to take care about the restart markers in
doSpecialFrameHandling():
(In reality, here I extended VideoRTPSink because I needed to, feel free to
do your adaptations)
u_int8_t RestartMarkerHeader[4]; // the special header
u_int16_t restartInterval = source->restartInterval();
RestartMarkerHeader[0] = restartInterval >> 8;
RestartMarkerHeader[1] = restartInterval;
RestartMarkerHeader[2] = 0xFF;
RestartMarkerHeader[3] = 0xFF;
setSpecialHeaderBytes(RestartMarkerHeader, sizeof RestartMarkerHeader, sizeof
mainJPEGHeader /* start position */);
Finally, reflect the size change in the headers in specialHeaderSize():
// We assume that there are 'restart markers'
headerSize += 4;
--
Belloni Cristiano
Imavis Srl.
www.imavis.com
bell...@imavis.com
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