[FFmpeg-cvslog] avdevice/decklink: remove pthread dependency
Aaron Levinson
git at videolan.org
Sat Apr 15 13:38:48 EEST 2017
ffmpeg | branch: master | Aaron Levinson <alevinsn at aracnet.com> | Sat Apr 15 08:41:46 2017 +0200| [9e86a61870c1652cdcc6a34646aee40d973ba23b] | committer: Marton Balint
avdevice/decklink: remove pthread dependency
Purpose: avdevice/decklink: Removed pthread dependency by replacing
semaphore used in code appropriately. Doing so makes it easier to
build ffmpeg using Visual C++ on Windows. This is a contination of
Kyle Schwarz's "avdevice/decklink: Remove pthread dependency" patch
that is available at https://patchwork.ffmpeg.org/patch/2654/ . This
patch wasn't accepted, and as far as I can tell, there was no
follow-up after it was rejected.
Notes: Used Visual Studio 2015 (with update 3) for this.
Comments:
-- configure: Eliminated pthreads dependency for decklink_indev_deps
and decklink_outdev_deps and replaced with threads dependency
-- libavdevice/decklink_common.cpp / .h:
a) Eliminated semaphore and replaced with a combination of a mutex,
condition variable, and a counter (frames_buffer_available_spots).
b) Removed include of pthread.h and semaphore.h and now using
libavutil/thread.h instead.
-- libavdevice/decklink_dec.cpp: Eliminated include of pthread.h and
semaphore.h.
-- libavdevice/decklink_enc.cpp:
a) Eliminated include of pthread.h and semaphore.h.
b) Replaced use of semaphore with the equivalent using a combination
of a mutex, condition variable, and a counter
(frames_buffer_available_spots). In theory, libavutil/thread.h and
the associated code could have been modified instead to add
cross-platform implementations of the sem_ functions, but an
inspection of the ffmpeg source base indicates that there are only
two cases in which semaphores are used (including this one that was
replaced), so it was deemed to not be worth the effort.
Signed-off-by: Marton Balint <cus at passwd.hu>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9e86a61870c1652cdcc6a34646aee40d973ba23b
---
configure | 4 ++--
libavdevice/decklink_common.cpp | 3 ---
libavdevice/decklink_common.h | 5 ++++-
libavdevice/decklink_dec.cpp | 3 ---
libavdevice/decklink_enc.cpp | 23 +++++++++++++++--------
5 files changed, 21 insertions(+), 17 deletions(-)
diff --git a/configure b/configure
index 98f7828489..3f2811a5b3 100755
--- a/configure
+++ b/configure
@@ -2995,9 +2995,9 @@ avfoundation_indev_deps="pthreads"
avfoundation_indev_extralibs="-framework Foundation -framework AVFoundation -framework CoreVideo -framework CoreMedia"
bktr_indev_deps_any="dev_bktr_ioctl_bt848_h machine_ioctl_bt848_h dev_video_bktr_ioctl_bt848_h dev_ic_bt8xx_h"
caca_outdev_deps="libcaca"
-decklink_indev_deps="decklink pthreads"
+decklink_indev_deps="decklink threads"
decklink_indev_extralibs="-lstdc++"
-decklink_outdev_deps="decklink pthreads"
+decklink_outdev_deps="decklink threads"
decklink_outdev_extralibs="-lstdc++"
dshow_indev_deps="IBaseFilter"
dshow_indev_extralibs="-lpsapi -lole32 -lstrmiids -luuid -loleaut32 -lshlwapi"
diff --git a/libavdevice/decklink_common.cpp b/libavdevice/decklink_common.cpp
index c9107c036a..f01fba953e 100644
--- a/libavdevice/decklink_common.cpp
+++ b/libavdevice/decklink_common.cpp
@@ -26,9 +26,6 @@
#include <DeckLinkAPIDispatch.cpp>
#endif
-#include <pthread.h>
-#include <semaphore.h>
-
extern "C" {
#include "libavformat/avformat.h"
#include "libavformat/internal.h"
diff --git a/libavdevice/decklink_common.h b/libavdevice/decklink_common.h
index 4753287ecf..c12cf18d70 100644
--- a/libavdevice/decklink_common.h
+++ b/libavdevice/decklink_common.h
@@ -24,6 +24,7 @@
#include <DeckLinkAPIVersion.h>
+#include "libavutil/thread.h"
#include "decklink_common_c.h"
class decklink_output_callback;
@@ -89,7 +90,9 @@ struct decklink_ctx {
int frames_preroll;
int frames_buffer;
- sem_t semaphore;
+ pthread_mutex_t mutex;
+ pthread_cond_t cond;
+ int frames_buffer_available_spots;
int channels;
};
diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
index 8cc1bdf7c9..67eaf97e89 100644
--- a/libavdevice/decklink_dec.cpp
+++ b/libavdevice/decklink_dec.cpp
@@ -21,9 +21,6 @@
#include <DeckLinkAPI.h>
-#include <pthread.h>
-#include <semaphore.h>
-
extern "C" {
#include "config.h"
#include "libavformat/avformat.h"
diff --git a/libavdevice/decklink_enc.cpp b/libavdevice/decklink_enc.cpp
index 18ef9058e2..5105967101 100644
--- a/libavdevice/decklink_enc.cpp
+++ b/libavdevice/decklink_enc.cpp
@@ -24,9 +24,6 @@ using std::atomic;
#include <DeckLinkAPI.h>
-#include <pthread.h>
-#include <semaphore.h>
-
extern "C" {
#include "libavformat/avformat.h"
#include "libavformat/internal.h"
@@ -91,7 +88,10 @@ public:
av_frame_unref(avframe);
- sem_post(&ctx->semaphore);
+ pthread_mutex_lock(&ctx->mutex);
+ ctx->frames_buffer_available_spots++;
+ pthread_cond_broadcast(&ctx->cond);
+ pthread_mutex_unlock(&ctx->mutex);
return S_OK;
}
@@ -133,7 +133,6 @@ static int decklink_setup_video(AVFormatContext *avctx, AVStream *st)
ctx->output_callback = new decklink_output_callback();
ctx->dlo->SetScheduledFrameCompletionCallback(ctx->output_callback);
- /* Start video semaphore. */
ctx->frames_preroll = st->time_base.den * ctx->preroll;
if (st->time_base.den > 1000)
ctx->frames_preroll /= 1000;
@@ -141,7 +140,9 @@ static int decklink_setup_video(AVFormatContext *avctx, AVStream *st)
/* Buffer twice as many frames as the preroll. */
ctx->frames_buffer = ctx->frames_preroll * 2;
ctx->frames_buffer = FFMIN(ctx->frames_buffer, 60);
- sem_init(&ctx->semaphore, 0, ctx->frames_buffer);
+ pthread_mutex_init(&ctx->mutex, NULL);
+ pthread_cond_init(&ctx->cond, NULL);
+ ctx->frames_buffer_available_spots = ctx->frames_buffer;
/* The device expects the framerate to be fixed. */
avpriv_set_pts_info(st, 64, st->time_base.num, st->time_base.den);
@@ -211,7 +212,8 @@ av_cold int ff_decklink_write_trailer(AVFormatContext *avctx)
if (ctx->output_callback)
delete ctx->output_callback;
- sem_destroy(&ctx->semaphore);
+ pthread_mutex_destroy(&ctx->mutex);
+ pthread_cond_destroy(&ctx->cond);
av_freep(&cctx->ctx);
@@ -247,7 +249,12 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt)
}
/* Always keep at most one second of frames buffered. */
- sem_wait(&ctx->semaphore);
+ pthread_mutex_lock(&ctx->mutex);
+ while (ctx->frames_buffer_available_spots == 0) {
+ pthread_cond_wait(&ctx->cond, &ctx->mutex);
+ }
+ ctx->frames_buffer_available_spots--;
+ pthread_mutex_unlock(&ctx->mutex);
/* Schedule frame for playback. */
hr = ctx->dlo->ScheduleVideoFrame((struct IDeckLinkVideoFrame *) frame,
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