Hi, 2014-06-11 11:51 GMT+02:00 Sam Jansen <sam.jan...@starleaf.com>: > Hi all, > > Thanks for the quick replies! > > > On 11 June 2014 05:54, Gwenole Beauchesne <gb.de...@gmail.com> wrote: >> >> Hi, >> >> 2014-06-10 20:33 GMT+02:00 Sam Jansen <sam.jan...@starleaf.com>: >> >> > I've been working on H264 encode, decode, and JPEG decode VA-API >> > programs >> > recently, using the Intel va-driver on Sandy Bridge and Bay Trail. >> > >> > This has gone well, but I've hit a problem with the H264 decoder in some >> > situations where I believe it is producing incorrect output. In some >> > cases >> > chroma, and less often luma, data does not agree with the reference >> > decoder >> > [1], often in Intra frames (but sometimes P frames too), always baseline >> > profile. I have an intra-encoded test stream where the 389th frame of a >> > stream encoded from the standard "paris (cif)" test stream is incorrect >> > on >> > both Sandy Bridge and Bay Trail. Many other test streams pass fine, >> > leaving >> > me to believe our decoder implementation is largely correct. >> > >> > I've also implemented a mode where I am able to get the current encoded >> > picture out of the VA-API encoder. I can then compare this, >> > byte-for-byte, >> > against a decode of the frame just encoded. I use this with out software >> > codecs to ensure our encode and decode match exactly. Using this >> > technique I >> > can easily compare our software codec, and the VA-API H264 codecs in any >> > combination. I've found the VA-API encode always agrees with our >> > decoder, >> > but the VA-API decoder does not always agree with the encode - either >> > our >> > software encoder or the VA-API encoder (this testing just on Bay Trail). >> > >> > I'd like to get to the bottom of this. The first step is removing our >> > decode >> > implementation from the test, and using one you believe to be good. What >> > tools do you use for regression testing? Is this perhaps ffmpeg invoked >> > in >> > some way? Is your test setup open source, such that I can modify it to >> > include my new test stream? >> >> The supported HW decoders that use VA-API and can be serve as >> reference are either GStreamer/vaapi, or FFmpeg/vaapi (for H.264). >> <http://gitorious.org/vaapi/gstreamer-vaapi/> >> >> Please provide me with a sample. We also have other tools, which I >> will publish later on. >> > > I've made it temporarily available at: > http://cam.starleaf.com/paris_cif_intra.264 > > Feel free to have a look at it. You're welcome to add it to whatever test > suite you have as well. However, I'm happy right now that I should first use > your gstreamer-vaapi to decode it, and check I get the same result there. I > would have thought the most likely explanation at this point in time is that > I have a bug in my VA-API H264 decoder -- I'd rather you didn't waste your > time on my bugs!
I have just tried your clip against our internal tools. I can confirm that gstreamer-vaapi decodes your file correctly on Ivybridge and produces bitexact output, as compared against JM. Likewise for FFmpeg/vaapi. I am afraid, that might be an issue in your code then. :) >> > PS: here's an extract of some of the chroma bytes where it has gone >> > right. >> > On the top, some bytes of reference decoder output, on the bottom, bytes >> > of >> > VA-API H264 decoder output. Note the 0x8f83 becomes 0x908f, then 0x8e8e >> > becomes 0x8d8d, the 0x8e8e becomes 0x8d8e. >> >> Note: how do you retrieve the bytes for comparison? If this is through >> vaGetImage(), the result of the conversion is generally not bitexact. >> > > I use vaDeriveImage(), which gives me a VA_FOURCC_NV12 image. I then > vaMapBuffer() it to get at the image data. > >> >> Regards, >> Gwenole. > > Regards, -- Gwenole Beauchesne Intel Corporation SAS / 2 rue de Paris, 92196 Meudon Cedex, France Registration Number (RCS): Nanterre B 302 456 199 _______________________________________________ Libva mailing list Libva@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libva