HWAccels with frame threads are fundamentally flawed in avcodecs current
design, and there are several known problems ranging from image corruption
to driver crashes.
These problems come down to two design problems in the interaction of
threads and HWAccel decoding:
(1)
While avcodec prevents parallel decoding and as such simultaneous access
to the hardware accelerator from the decoding threads, it cannot account
for the user code and its access to the hardware surfaces and the hardware
itself.
This can result in image corruption or even driver crashes if the
user code locks image surfaces while they are being used by the decoder
threads as reference frames.
The current HWAccel API does not offer any way to ensure exclusive access
to the hardware or the surfaces if frame threading is used.
(2)
Initialization of the HWAccel with frame threads is non-trivial, and many
decoders had and still have issues that cause excess calls to the
get_format callback.
This will potentially cause duplicate HWAccel initialization, which in
extreme cases can even lead to driver crashes if the HWAccel is
re-initialized while the user code is actively accessing the hardware
surfaces associated with it, or lead to image corruption due to lost
reference frames.
While both of these issues are solvable, fixing (1) would at least require
a huge API redesign which would move a lot of complexity into the user
code.
The only reason the combination of frame threads and HWAccel was
considered useful is to allow a seamless fallback to multi-threaded
software decoding if the HWAccel is not available, however the issues
outlined above far outweigh this.
The proper solution for a fallback is to re-open the AVCodecContext with
threading enabled if the HWAccel failed, which is a practice commonly used
by various user applications using avcodec today already.
Reviewed-by: Gwenole Beauchesne <gb.devel@gmail.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Hendrik Leppkes <h.leppkes@gmail.com>
The Apple dev specification:
https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/Metadata/Metadata.html
Basically the structure is like:
|--meta
|----hdlr
|----keys
|----ilst
1) The handler type in the metadata handler atom is ‘mdta’.
2) The key and value are stored separately for each key-value pair.
The 'keys' atom stores the key table, while 'ilst' atom stores the
values corresponding to the indices in the key table.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
This fixes a fate failure after bumping the minor version
Its unknown why this is not needed for the other aac tests,
more investigation needed but for now i dont want to leave
it broken while its investigated
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Commit 7c8fcbbde3 introduced some warnings
that get triggered on the test build. This should fix them.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This adds const-correctness when needed for the comparators.
Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
libc's qsort comparator has a const qualifier on both arguments. This
adds a missing const qualifier to exactly match the comparator API.
Existing usages of av_tree_find, av_tree_insert are appropriately
modified: type signature changes of the comparators, and removal of
unnecessary void * casts of function pointers.
Reviewed-by: Henrik Gramner <henrik@gramner.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This documents the additional constness, and provides a useful libc
reference for the API specification of the comparator.
Reviewed-by: Henrik Gramner <henrik@gramner.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
For generality, qsort uses a comparator whose elements are void *. This
makes the comparator have such a form, and thus makes the void * cast of
the comparator pointer useless. Furthermore, this makes the code more
consistent with other usages of qsort across the codebase.
Reviewed-by: Henrik Gramner <henrik@gramner.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This fixes extra semicolons that clang 3.7 on GNU/Linux warns about.
These were trigggered when built under -Wpedantic, which essentially
checks for strict ISO compliance in numerous ways.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
These casts are unnecessary, and may safely be removed.
Found by enabling -Wpedantic on clang 3.7.
Tested with FATE.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
ISO C requires at least one argument in the place of the ellipsis in a
variadic macro. In particular, under -pedantic, this triggers the
warning -Wgnu-zero-variadic-macro-arguments on clang 3.7.
Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Current code segfaults since the deprecation of AVSubtitleRect.pict because it
freed/realloced AVSubtitleRect.pict.data by itself.
The new code stores the generated YUVA AVSubtitle rectangles in their own
struct and keeps the original AVSubtitle structure untouched, because
overwriting it is considered invalid API usage.
Signed-off-by: Marton Balint <cus@passwd.hu>
Hendrik Leppkes
Rostislav Pehlivanov
Timothy Gu
James Almer
Kieran Kunhya
Michael Niedermayer
Kyle Swanson
Clément Bœsch
Derek Buitenhuis
Tinglin Liu
Vittorio Giovara
Ganesh Ajjanagadde
Paul B Mahol
Clément Bœsch
Nicolas George
Carl Eugen Hoyos
Ronald S. Bultje
Marton Balint