When an audio filter is applied to a video source that also has
accompanying audio, it would cause the video from the source to stop
rendering.
The original code this was from was to prevent audio-only sources from
rendering video, but I neglected to make sure that this would not apply
to filters, and thus when an audio filter is on a source with video, the
code would kill the video.
Due to the fact that async timestamps themselves can be susceptible to
minor jitter from certain types of inputs, increase the allowable jitter
compensation value to ensure that the rendered frame timing from async
video sources is always as close as possible to the compositor.
When the framerate of the source is the same as the framerate as the
compositor, this (combined with the fact that clamped video timing now
being used with async video frames) helps ensure that buffered async
video sources will sync up their rendering to the compositor as
accurately as possible despite jitter from the source's timestamps.
If there is no jitter in the source's timestamps then it'll always sync
up perfectly with the compositor, thanks to clamped video timing.
When playing back buffered async frames, this reduces the probability
that new frames will be missed/skipped due to jitter in the system
timestamps.
If a buffered async source is playing at the same framerate as the
compositor and there is no jitter in the async source's timestamps, then
the async source will play back perfectly in sync with the compositor
thanks to this change, ensuring that there's no skipped or missed frames
in video playback.
When buffering is enabled for an async video source, sometimes minor
drift in timestamps or unexpected delays to frames can cause frames to
slowly buffer more and more in memory, in some cases eventually causing
the system to run out of memory.
The circumstances in which this can happen seems to depend on both the
computer and the devices in use. So far, the only known circumstances
in which this happens are with heavily buffered devices, such as
hauppauge, where decoding can sometimes take too long and cause
continual frame playback delay, and thus continual buffering until
memory runs out. I've never been able to replicate it on any of my
machines however, even after hours of testing.
This patch is a precautionary measure that puts a hard limit on the
number of async frames that can be currently queued to prevent any case
where memory might continually build for whatever reason. If it goes
over the limit, it clears the cache to reset the buffering.
I had a user with this problem test this patch with success and positive
feedback, and the intervals between buffering resets were long to where
it wasn't even noticeable while streaming/recording.
Ideally when decoding frames (such as from those devices), frame
dropping should be used to ensure playback doesn't incur extra delay,
although this sort of hard limit on the frame cache should still be
implemented regardless just as a safety precaution. For DirectShow
encoded devices I should just switch to faruton's libff for decoding and
enable the frame dropping options. It would probably explain why no
one's ever reported it for the media source, and pretty much only from
DirectShow device usage.
Fixes a crash that could happen if any of the mutexes are used in the
create callback, or before the obs_source_init function is called.
I'm not sure how this function order slipped because it seems fairly
obvious that these mutexes should be created before the create callback.
Had this crash happen to me when creating a WASAPI output source, the
create callback of the WASAPI source creates a thread which outputs
audio, and that thread managed to call obs_source_output_audio before
the obs_source_init function was called, which in turn caused it to try
to use a null mutex.
When caching a new frame, keep a reference to the frame while copying to
ensure that the frame is not potentially destroyed for whatever reason
while that data is being copied.
The obs_source::async_reset_texture variable can cause a data race
between threads to occur because it could be set to true in one thread
then changed back to false in another thread. This could cause the
async texture to not update its size when it's supposed to, which can
cause a crash or corruption when copying data from a frame of a
differing size.
The solution to this is to:
- Delete the async_reset_texture variable, and make the
set_async_texture_size function change the texture size if the
async_width, async_height, or async_format variables differ from the
frame's width/height/format. Those variables are then only ever set
in the libobs graphics thread.
- Make the cache_video function use separate variables from other
functions to detect a change in size (due to the fact that the texture
size should only be resized in the libobs graphics thread). These
variables are async_cache_width, async_cache_height, and
async_cache_format, which are only be set in the thread that calls
obs_source_output_video.
How to replicate the data race:
- On OSX, use window capture on a textedit window, then continually
resize the textedit window.
Due to a bad 'if' expression, when a filter that is not last in the
chain is disabled or being bypassed, it ends up still calling the
filter's video processing function unintentionally.
This fix makes sure that it only calls the appropriate render functions
if the next filter target is the source, otherwise it will just call
obs_source_video_render to process the next filter in the chain.
How to replicate the bug:
1. Create two crop filters on the same source
2. Give each crop filter a different distinct value
3. Disable both crop filters
4. The image would still be cropped
This fixes an issue where cache frames would not free at all after
having been allocated with no upper limit on the cached frame size. If
cached frames go unused for a specific period of time, they are
deallocated and removed from the cache.
This is preferable to having an upper cache limit due to the potential
for async delay filtering.
Under certain circumstances the cache could be prone to growing too
large unintentionally. Setting a hard maximum limit should prevent
memory from growing if we suddenly get a lot of frames.
Async frames are only swapping when rendering, or when not visible.
This is a flawed design due to the fact that there are certain
circumstances where the source is neither visible nor currently
rendering.
This is what caused a memory leak when scene items were marked as
invisible, because if a source has an async child source and decides not
to render that source for whatever reason, the child source would not
process the async frames at all, and the cache would just grow.
To fix this, simply moving the async frame cycle to tick fixes the issue
due to the fact that tick is always called regardless of circumstance.
Filtering the video before it's output to the texture means that it
happens after all the processing on the timestamps and such of the video
data. This way, the video filter does not have to worry about what's
currently buffered, and it won't affect timing.
When OBS is shutting down, if for some reason the filter is destroyed
before the parent source is destroyed, it would try to remove itself
from the source, but it would decrement the reference and try to destroy
itself again while already in the process of destroying itself.
So, the solution was simply to make sure that if it's removing itself
from the source that it doesn't decrement its own reference.
The "last" filter that's rendered is technically at filter index 0, so
enumeration needs to be from the last index in the list to the first
index in the list.
When rendering a filter to a texture, the target is empty and unused, so
there's no reason for blending to be on when rendering the filter to a
render target.
obs_source_process_filter tried to do everything in a single function,
but the problem is that effect parameters would not properly be
accounted for due to the way it internally draws, therefore it was
necessary to split the functions in to two, you first call
obs_source_process_filter_begin, then you set your effect parameters,
then you finally call obs_source_process_filter_end. This ensures that
when the filter is drawn, that the effect parameters are set.
When the filter chain finally reaches the source and the last filter in
the chain is set to not render directly (meaning it has to render to
texture), it would not render the source with any effect due to the fact
that it expects a filter to be present.
Adds a source callback function that is used when a filter is removed
from a source. This ensures that any data that might be associated with
that source can be cleaned up if necessary.
There are a few more conditions which need to be checked to ensure
whether we can actually bypass or not; in this particular case we are
using the YUV texture shaders, plus the image can also be flipped, so we
can't really use the bypass optimization in those situations.
These functions are primarily for use with filters, filters need to be
able to get the width/height of a target source without it necessarily
getting the post-filtered dimensions.
Previously I had it set so that it would set the async_width and
async_height variables to 0,0 if a null frame occurs, but the problem
with this is that it was inadvertently cause the frame cache to clear
when it starts receiving textures again because it detects it as a size
change.
So instead of changing async_width and async_height to 0 when a null
frame occurs, change it so that if the source is set to an inactive
state, make obs_source_get_width/_get_height return 0 for their
dimensions instead.
When a frame is processed by a filter, it comes directly from the
source's video frame cache. However, if a filter is using or processing
those frames for whatever reason, there would be no guarantee that the
frames would persist during processing, and frames could eventually be
deallocated unexpected, for example when the resolution or format
changes.
So the solution is to implement simple reference counting for the frames
so that the frames will exist until they have been released by any
source or filter that's using them.
Fix a bug where when a source first starts up its async cache, it
unintentionally resets its cache, which means that the first few frames
would be lost.
The wrong function was being used to recurse through the filter chain in
obs_source_process_filter, obs_source_get_[width/height] would get the
post-effect dimensions rather than the pre-effect dimensions.
jp9000
Palana