sysutils/ffmpeg
1
0
Fork 0
mirror of https://git.ffmpeg.org/ffmpeg.git synced 2026-10-24 02:09:03 +03:00
Code Activity

avfilter/vf_yadif_videotoolbox: fix over-release of autoreleased Metal objects

Browse Source 
call_kernel() obtains the command buffer and compute encoder from
property getters (mtlQueue.commandBuffer, buffer.computeCommandEncoder),
which return autoreleased references under the non-ARC build, and then
releases them via ff_objc_release(). That is an over-release: when the
enclosing autorelease pool is drained, the objects are released a second
time and the process crashes with EXC_BAD_ACCESS in objc_release.

On current macOS this is reproducible with the ffmpeg CLI itself. The
filter thread's thread-local autorelease pool is popped during pthread
TSD cleanup at thread exit, so any run that used yadif_videotoolbox
crashes when the filter thread terminates:

  ffmpeg -init_hw_device videotoolbox=vt -filter_hw_device vt \
    -f lavfi -i testsrc2=size=640x480:rate=30 \
    -vf setfield=tff,format=nv12,hwupload,yadif_videotoolbox,\
  hwdownload,format=nv12 -frames:v 20 -f null -

  Thread 11 Crashed:: vf#0:0
  0 libobjc.A.dylib  objc_release + 16
  1 libobjc.A.dylib  AutoreleasePoolPage::releaseUntil(objc_object**) + 204
  2 libobjc.A.dylib  objc_autoreleasePoolPop + 244
  3 libobjc.A.dylib  objc_tls_direct_base<...>::dtor_(void*) + 156
  4 libsystem_pthread.dylib  _pthread_tsd_cleanup + 620
  5 libsystem_pthread.dylib  _pthread_exit + 84

Host applications hit the same crash earlier, for example when a
dispatch queue drains its last-resort pool after a work item that ran
the filter.

Wrap the kernel invocation in @autoreleasepool and drop the manual
releases, making the pool pop the single balanced release and draining
the Metal transients once per frame. The ff_objc_release() calls on the
s->mtl* members in do_uninit() stay: those hold owned references
obtained from new* methods.

(cherry picked from commit 7f2e5cdd7c)
This commit is contained in:
Vincent Herbst
2026-07-19 20:09:29 +02:00
committed by ffmpeg-devel
parent f1000559d1
commit b5d146d17c
1 changed files with 22 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
libavfilter/vf_yadif_videotoolbox.m
View File

@@ -72,31 +72,30 @@ static void call_kernel(AVFilterContext *ctx,
int tff) API_AVAILABLE(macos(10.11), ios(8.0))
{
YADIFVTContext *s = ctx->priv;
id<MTLCommandBuffer> buffer = s->mtlQueue.commandBuffer;
id<MTLComputeCommandEncoder> encoder = buffer.computeCommandEncoder;
struct mtlYadifParams *params = (struct mtlYadifParams *)s->mtlParamsBuffer.contents;
*params = (struct mtlYadifParams){
.channels = channels,
.parity = parity,
.tff = tff,
.is_second_field = !(parity ^ tff),
.skip_spatial_check = s->yadif.mode&2,
.field_mode = s->yadif.current_field
};
@autoreleasepool {
id<MTLCommandBuffer> buffer = s->mtlQueue.commandBuffer;
id<MTLComputeCommandEncoder> encoder = buffer.computeCommandEncoder;
struct mtlYadifParams *params = (struct mtlYadifParams *)s->mtlParamsBuffer.contents;
*params = (struct mtlYadifParams){
.channels = channels,
.parity = parity,
.tff = tff,
.is_second_field = !(parity ^ tff),
.skip_spatial_check = s->yadif.mode&2,
.field_mode = s->yadif.current_field
};
[encoder setTexture:dst atIndex:0];
[encoder setTexture:prev atIndex:1];
[encoder setTexture:cur atIndex:2];
[encoder setTexture:next atIndex:3];
[encoder setBuffer:s->mtlParamsBuffer offset:0 atIndex:4];
ff_metal_compute_encoder_dispatch(s->mtlDevice, s->mtlPipeline, encoder, dst.width, dst.height);
[encoder endEncoding];
[encoder setTexture:dst atIndex:0];
[encoder setTexture:prev atIndex:1];
[encoder setTexture:cur atIndex:2];
[encoder setTexture:next atIndex:3];
[encoder setBuffer:s->mtlParamsBuffer offset:0 atIndex:4];
ff_metal_compute_encoder_dispatch(s->mtlDevice, s->mtlPipeline, encoder, dst.width, dst.height);
[encoder endEncoding];
[buffer commit];
[buffer waitUntilCompleted];
ff_objc_release(&encoder);
ff_objc_release(&buffer);
[buffer commit];
[buffer waitUntilCompleted];
}
}
static void filter(AVFilterContext *ctx, AVFrame *dst,