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. > 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. Regards, Gwenole. _______________________________________________ Libva mailing list Libva@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libva
