y_offset and y_coeff being successive 32-bit integers, they are packed
into 8 bytes instead of 2x8 bytes.
See https://developer.apple.com/library/ios/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARM64FunctionCallingConventions.html
> iOS diverges from Procedure Call Standard for the ARM 64-bit
> Architecture in several ways
[...]
> In the generic procedure call standard, all function arguments passed
> on the stack consume slots in multiples of 8 bytes. In iOS, this
> requirement is dropped, and values consume only the space required.
[...]
> Padding is still inserted on the stack to satisfy arguments’ alignment
> requirements.
Fix a dead lock under certain conditions. Let's assume we have a queue of 1
message max, 2 senders, and 1 receiver.
Scenario (real record obtained with debug added):
[...]
SENDER #0: acquired lock
SENDER #0: queue is full, wait
SENDER #1: acquired lock
SENDER #1: queue is full, wait
RECEIVER: acquired lock
RECEIVER: reading a msg from the queue
RECEIVER: signal the cond
RECEIVER: acquired lock
RECEIVER: queue is empty, wait
SENDER #0: writing a msg the queue
SENDER #0: signal the cond
SENDER #0: acquired lock
SENDER #0: queue is full, wait
SENDER #1: queue is full, wait
Translated:
- initially the queue contains 1/1 message with 2 senders blocking on
it, waiting to push another message.
- Meanwhile the receiver is obtaining the lock, read the message,
signal & release the lock. For some reason it is able to acquire the
lock again before the signal wakes up one of the sender. Since it
just emptied the queue, the reader waits for the queue to fill up
again.
- The signal finally reaches one of the sender, which writes a message
and then signal the condition. Unfortunately, instead of waking up
the reader, it actually wakes up the other worker (signal = notify
the condition just for 1 waiter), who can't push another message in
the queue because it's full.
- Meanwhile, the receiver is still waiting. Deadlock.
This scenario can be triggered with for example:
tests/api/api-threadmessage-test 1 2 100 100 1 1000 1000
One working solution is to make av_thread_message_queue_{send,recv}()
call pthread_cond_broadcast() instead of pthread_cond_signal() so both
senders and receivers are unlocked when work is done (be it reading or
writing).
This second solution replaces the condition with two: one to notify the
senders, and one to notify the receivers. This prevents senders from
notifying other senders instead of a reader, and the other way around.
It also avoid broadcasting to everyone like the first solution, and is,
as a result in theory more optimized.
This makes the sorting of the colors along an axis (r, g or b)
predictible, and thus testable under FATE. The performance is not really
an issue here since the function is called only once at the end and will
need to sort very small number of entries, so an alternative would be to
make the sorting functions (see DECLARE_CMP_FUNC()) fallback on another
axis in case of equality. This approach was actually simpler.
I don't know if there is any advantage in using a multidimensional sort,
but it will affect the final palette one way or another.
Fixes the following link error:
nutdec.c:(.text+0x2d47): undefined reference to `ff_codec_movvideo_tags'
isom.c:(.text+0x332): undefined reference to `avpriv_mpeg4audio_get_config'
isom.c:(.text+0x39e): undefined reference to `avpriv_mpa_freq_tab'
The reasoning behind this addition is that various third party
applications are interested in getting some motion information out of a
video "for free" when it is available.
It was considered to export other information as well (such as the intra
information about the block, or the quantization) but the structure
might have ended up into a half full-generic, half full of codec
specific cruft. If more information is necessary, it should either be
added in the "flags" field of the AVMotionVector structure, or in
another side-data.
This commit also includes an example exporting them in a CSV stream.
Clément Bœsch