On Thu, Jul 8, 2010 at 3:19 PM, Daniel P. Berrange <berra...@redhat.com> wrote: > On Thu, Jul 08, 2010 at 03:10:31PM +0200, Corentin Chary wrote: >> On Thu, Jul 8, 2010 at 11:48 AM, Daniel P. Berrange <berra...@redhat.com> >> wrote: >> > On Wed, Jul 07, 2010 at 08:57:56PM +0200, Corentin Chary wrote: >> >> Introduce a new encoding: VNC_ENCODING_TIGHT_PNG [1] (-269) with a new >> >> tight filter VNC_TIGHT_PNG (0x0A). When the client tells it supports the >> >> Tight PNG >> >> encoding, the server will use tight, but will always send encoding pixels >> >> using >> >> PNG instead of zlib. If the client also told it support JPEG, then the >> >> server can >> >> send JPEG, because PNG will only be used in the cases zlib was used in >> >> normal tight. >> > >> > I know that VNC_ENCODING_TIGHT_PNG / -260 is already allocated to >> > QEMU in the RFB specification. Who is the authority for allocating >> > tight filter numbers, and have they recorded/approved use of 0x0A >> > for this PNG capability ? >> > >> >> Tight PNG should considered as a new encoding, not as a tight pseudo >> encoding. >> When using Tight PNG, the server will send rect updates with -260, not 7. > > Why layer this into the rest of the Tight protocol decoding then ? What > benefit does it offer over a more straightforward standalone "PNG" encoding, > that was completely independant of any tight based encoding. >
Because: - we also want a lossy encoding (Jpeg) for some parts (adaptive choice between jpeg and png/zlib based on update frequency is comming soon). - we want the "fill" encoding for solid color rectangles A standalone "PNG" encoding would work for some use case, and could be added later, but Tight PNG is more than that. -- Corentin Chary http://xf.iksaif.net
