As previously discussed, the CrystalHD hardware returns exceptionally
useless information about interlaced h.264 content - to the extent
that it's not possible to distinguish most MBAFF and PAFF content until
it's too late.
In an attempt to compensate for this, I'm introducing two mechanisms:
1) Peeking at the picture number of the next picture
The hardware provides a capability to peek the next picture number. If
it is the same as the current picture number, then we are clearly dealing
with two fields and not a frame or fieldpair.
If this always worked, it would be all we need, but it's not guaranteed
to work. Sometimes, the next picture may not be decoded sufficiently
for the number to be known; alternately, a corruption in the stream may
cause the hardware to refuse to return the number even if the next
intact frame is decoded. In either case, the query will return 0.
If we are unable to peek the next picture number, we assume that the
picture is a frame/fieldpair and return it accordingly. If that turns
out to be incorrect, we discard the second field, and the user has
to live with the glitch. In testing, false detection can occur for
the first couple of seconds, and then the pipeline stabalizes and
we get correct detection.
2) Use the h264_parser to detect when individual input fields have
been combined into an output fieldpair.
I have multiple PAFF samples where this behaviour is detected. The
peeking mechanism described above will correctly detect that the
output is a fieldpair, but we need to know what the input type was
to ensure pipeline stability (only return one output frame per input
frame).
If we find ourselves with an output fieldpair, yet the input picture
type was a field, as reported by the parser, then we are dealing with
this case, and can make sure not to return anything on the next
decode() call.
Taken together, these allow us to remove the hard-coded hacks for
different h.264 types, and we can clearly describe the conditions
under which we can trust the hardware's claim that content is
interlaced.
Signed-off-by: Philip Langdale <philipl@overt.org>
Now that we know the type of the input picture, we have to bring
that information to the output picture to help identify its type.
We do this by adding a field to the opaque_list node.
Signed-off-by: Philip Langdale <philipl@overt.org>
As the hardware is unreliable, we will have to use the h.264 parser
to identify whether an input picture is a field or a frame. This
change loads the parser and extracts the picture type.
Signed-off-by: Philip Langdale <philipl@overt.org>
In preparation for adding additional fields to the node, return
the node instead of the pts value. This requires the caller to
free the node.
Signed-off-by: Philip Langdale <philipl@overt.org>
I found another MBAFF sample where the input:output pattern is
the same as mpeg2 and vc1 (fieldpair input, individual field output).
While I'm not sure how you can output individual fields from MBAFF,
if I apply the mpeg2/vc1 handling to this file, it plays correctly.
So, this changes the detection algorithm to handle the known cases.
Whitespace will be fixed in a separate change.
Signed-off-by: Philip Langdale <philipl@overt.org>
As previously discussed, the CrystalHD hardware treats some PAFF
clips different from others; even when input fields are always in
separate packets, the hardware might return a single fieldpair for
one clip and individual fields for another.
Given the bogus flags set by the hardware, it is impossible to
distinguish these two cases without knowing about the current
picture and the next one. The hardware can usually provide the
picture number of the next picture and when that is available,
we can detect the two cases.
When it is not available, we have to guess - and find out later
if we were right or wrong.
With this change, clips will play correctly unless they are PAFF
where individual fields are returned *and* no next picture number
is available. Generally speaking, the incorrect cases arise in
the first couple of seconds of a clip as the delay calibration takes
place. Once that's set, things work fine.
As previously discussed, the CrystalHD hardware returns exceptionally
useless information about interlaced h.264 content - to the extent
that it's not possible to distinguish MBAFF and PAFF content until
it's too late.
This change introduces use of the h264_parser to help bridge the
gap; it can indicate if the input data is PAFF fields or not.
With this clarity, some of heuristics can be removed from the code,
making this less convoluted.
Finally, I found an MBAFF clip that acts like non h.264 content so
I had to make allowances for that.
Note that I still cannot distinguish between two forms of PAFF,
where the hardware either returns individual fields or a field-pair.
It's not clear that there's even a spec relevant difference between
the two forms, as opposed to hardware ideosyncracies.
The Broadcom CrystalHD decoder chips provide hardware video
decoding for a number of video formats. It does so using a
memory:memory interface where a compressed bitstream is fed
in and decompressed pictures are copied out. As such, it works
independent of any graphics hardware in the system.
Features supported in this initial version:
* Support for Linux (using current drivers/library from git.wilsonet.com)
* Support for 70015 hardware
* Formats: MPEG2, MPEG4 Part 2, H.264, VC1 and DivX 3.11 (untested)
* Progressive content
* Non-H.264 Interlaced content
* H.264 MBAFF content
Features missing in this initial version:
* Support for OSX (might work - untested)
* Support for Windows
* Support for 70012 hardware
* H.264 PAFF content
Signed-off-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
