[Live-devel] JPEG Video RTP Source ignores quantization table precision

[Ross Finlayson]

> On Feb 17, 2018, at 4:13 AM, Joshua Hitchen <Josh at metrosecurity.co.uk> wrote:
> 
> Hi,
> Sorry to bother you on something potentially purposeful – it just seems like you may have meant to temporarily remove this functionality given that some of the code for it exists but is commented out.
> In JPEGVideoRTPSource.cpp you set the precision in the DQT segments to 0 (meaning 8 bit), even though the corresponding sink supports setting the precision via a call to the quantizationTables method.

This may (perhaps) have been an oversight.  The “JPEGVideoRTPSource” code basically just implements the code that’s in Appendix B of RFC 2435 (which defines the RTP payload format for JPEG video).  I.e., it transforms the information that was in the special RTP JPEG header (and quantization tables, if present) into a corresponding JPEG image header.  It’s possible that this code is incomplete.

If you’re sure about this, feel free to propose a patch to “JPEGVideoRTPSource.cpp"


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/