On 22/01/2018 12:20, Li, Zhong wrote:
MSDK provides an API (MFXVideoDECODE_DecodeHeader) to parse video
parameters. Currently it hasn't been used. Instead, software parsers
are used. It works well for h264 decoder, and basically works well
for hevc decoder (some issues found by Mayxm due to width/height are
unaligned, I also found some hevc clips without setting profile can
be decoded by software but qsv failed) . More issues found on other
decoders such as VP8. The decoding conformance pass rate is low and
looks like it is due to some missing/incompatible header information
is passed to qsv decoder (though Mark provides a patch 182cf17 but
still something is missing). Similar issues happens on MJPEG decoding
which I am going to add. Maybe we can continue to work on software
parsers for qsv, but I believe replace software parser with
MFXVideoDECODE_DecodeHeader is a better choice:
1. It can remove the dependence on various software parsers, and
just need a unified interface for all codes.
2. It will be very easy to add new decoder such as MJPEG
decoding support without any software parser patches.
3. MFXVideoDECODE_DecodeHeader is used by MSDK sample decoder
(i.e: sample_decode), so it is reliable for MSDK decoder. (As my
test, it can effectively improve decoding conformance pass rate,
especially for vp8 decoding.)
4. CUVID decoder is using CUVID parser instead of software
parser, maybe qsv can align with it.
No it is not, in Libav the CUVID support is implemented as hwaccel1, so
it leverages the software decoder for the parsing and a little more.
In my opinion it boils down to either have a uniform behavior in parsing
and formatting the input with its many quirks or using more of the
hwaccel/sdk.
I do not have a strong opinion in this regard.
lu
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