RTP Payload Format for ISO/IEC 21122 (JPEG XS)
Note about the RTP payload packetization modes for IP Media worflows
Two RTP packetization modes are standardized in the JPEG XS payload offering more flexibility to implementers: A Codestream mode and A Slice-based mode.
The main difference is that the "Codestream mode" is sending the coded data in a raster scan order while the "Slice-based mode" enable to send the coded in a non-sequential transmission.
intoPIX recommends to apply (by default) the "Codestream packetization mode" for XS RTP payload. While it is offering the lowest latency of XS coding & decoding in all implementations: FPGA , CPU & GPU, the codestream packetisation mode offers also the following benefits:
- Better quality encoding & efficiency in JPEG-XS keeping on-the-fly constant bitrate coding (few lines of latency , below the frame)
- A direct remapping (no latency penalty) between RTP (ST 2110-22) and MPEG2-TS (ST 2022-2) without the need of parsing the codestream.
- A direct remapping (no latency penalty) between RTP (ST2110-22) and MXF without the need of parsing the codestream
In contrary : the Slice-based packetization mode might be recommended in case of a non-sequential transmission of the codestream. It has a drawback in interoperability - causing other latency penalties in workflows, but might reduce the latency in the particular usage of some GPU. (This non-sequential benefits has not/never been proven and is difficult to make interoperable with hardware implementation (FPGA) & CPU.)