Hi Philipp, Thanks a lot for working on this. I'm so glad about both efforts: the CODA JPEG support and the JPEG helpers. On Wed, 2019-11-13 at 16:05 +0100, Philipp Zabel wrote: > Hi, > > as far as I can tell we currently have three JPEG header parsers in the > media tree (in the rcar_jpu, s5p-jpeg, and mtk-jpeg drivers). I would > like to add support for the CODA960 JPEG decoder to the coda-vpu driver > without adding yet another. > > To this end, this patch series adds some common JPEG code to v4l2-core. > For now this just contains header parsing helpers (I have tried to keep > the terminology close to JPEG ITU-T.81) that should be usable for all of > the current drivers. In the future we might want to move JPEG header > generation for encoders and common quantization tables in there as well. > Indeed, moving encoders to use these helpers sounds like the right thing to do. IIRC, quantization tables are implementation defined, and not imposed by anything. I believe gspca drivers use some tables that don't follow any recomendation. I guess it's fine to leave some drivers unconverted, without using any helpers, and move others to use a helper-derived quantization table. > I have tested this on hardware only with coda-vpu, the other drivers are > just compile-tested. > > Feedback very welcome, especially whether this actually works for the > other drivers, and if this could be structured any better. I'm a bit > unhappy with the (current) need for separate frame/scan header and > quantization/hfufman table parsing functions, but those are required > by s5p-jpeg, which splits localization and parsing of the marker > segments. Also, could this be used for i.MX8 JPEGDEC as is? > [..] Regards, Ezequiel
