Hi Tomasz, On Tue, 2018-07-24 at 23:06 +0900, Tomasz Figa wrote: > This series attempts to add the documentation of what was discussed > during Media Workshops at LinuxCon Europe 2012 in Barcelona and then > later Embedded Linux Conference Europe 2014 in Düsseldorf and then > eventually written down by Pawel Osciak and tweaked a bit by Chrome OS > video team (but mostly in a cosmetic way or making the document more > precise), during the several years of Chrome OS using the APIs in > production. > > Note that most, if not all, of the API is already implemented in > existing mainline drivers, such as s5p-mfc or mtk-vcodec. Intention of > this series is just to formalize what we already have. > > It is an initial conversion from Google Docs to RST, so formatting is > likely to need some further polishing. It is also the first time for me > to create such long RST documention. I could not find any other instance > of similar userspace sequence specifications among our Media documents, > so I mostly followed what was there in the source. Feel free to suggest > a better format. > > Much of credits should go to Pawel Osciak, for writing most of the > original text of the initial RFC. > > Changes since RFC: > (https://lore.kernel.org/patchwork/project/lkml/list/?series=348588) > - The number of changes is too big to list them all here. Thanks to > a huge number of very useful comments from everyone (Philipp, Hans, > Nicolas, Dave, Stanimir, Alexandre) we should have the interfaces much > more specified now. The issues collected since previous revisions and > answers leading to this revision are listed below. Thanks a lot for the update, and especially for the nice Q&A summary of the discussions so far. [...] > Decoder issues > [...] > How should ENUM_FRAMESIZES be affected by profiles and levels? > > Answer: Not in current specification - the logic is too complicated and > it might make more sense to actually handle this in user space. (In > theory, level implies supported frame sizes + other factors.) For decoding I think it makes more sense to let the hardware decode them from the stream and present them as read-only controls, such as: 42a68012e67c ("media: coda: add read-only h.264 decoder profile/level controls") if possible. For encoding, the coda firmware determines level from bitrate and coded resolution, itself, so I agree not making this part of the spec is a good idea for now. regards Philipp
