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.
Unified · Split
| @@ -2995,9 +2995,9 @@ avfoundation_indev_deps="pthreads" · 2994 unmodified lines | ||
| 2995 | 2995 | avfoundation_indev_extralibs="-framework Foundation -framework AVFoundation -framework CoreVideo -framework CoreMedia" |
| 2996 | 2996 | bktr_indev_deps_any="dev_bktr_ioctl_bt848_h machine_ioctl_bt848_h dev_video_bktr_ioctl_bt848_h dev_ic_bt8xx_h" |
| 2997 | 2997 | caca_outdev_deps="libcaca" |
| 2998 | −decklink_indev_deps="decklink pthreads" | |
| 2998 | +decklink_indev_deps="decklink threads" | |
| 2999 | 2999 | decklink_indev_extralibs="-lstdc++" |
| 3000 | −decklink_outdev_deps="decklink pthreads" | |
| 3000 | +decklink_outdev_deps="decklink threads" | |
| 3001 | 3001 | decklink_outdev_extralibs="-lstdc++" |
| 3002 | 3002 | dshow_indev_deps="IBaseFilter" |
| 3003 | 3003 | dshow_indev_extralibs="-lpsapi -lole32 -lstrmiids -luuid -loleaut32 -lshlwapi" |
| @@ -26,9 +26,6 @@ · 25 unmodified lines | ||
| 26 | 26 | #include <DeckLinkAPIDispatch.cpp> |
| 27 | 27 | #endif |
| 28 | 28 | |
| 29 | −#include <pthread.h> | |
| 30 | −#include <semaphore.h> | |
| 31 | − | |
| 32 | 29 | extern "C" { |
| 33 | 30 | #include "libavformat/avformat.h" |
| 34 | 31 | #include "libavformat/internal.h" |
| @@ -24,6 +24,7 @@ · 23 unmodified lines | ||
| 24 | 24 | |
| 25 | 25 | #include <DeckLinkAPIVersion.h> |
| 26 | 26 | |
| 27 | +#include "libavutil/thread.h" | |
| 27 | 28 | #include "decklink_common_c.h" |
| 28 | 29 | |
| 29 | 30 | class decklink_output_callback; |
| @@ -89,7 +90,9 @@ struct decklink_ctx { · 59 unmodified lines | ||
| 89 | 90 | int frames_preroll; |
| 90 | 91 | int frames_buffer; |
| 91 | 92 | |
| 92 | − sem_t semaphore; | |
| 93 | + pthread_mutex_t mutex; | |
| 94 | + pthread_cond_t cond; | |
| 95 | + int frames_buffer_available_spots; | |
| 93 | 96 | |
| 94 | 97 | int channels; |
| 95 | 98 | }; |
| @@ -21,9 +21,6 @@ · 20 unmodified lines | ||
| 21 | 21 | |
| 22 | 22 | #include <DeckLinkAPI.h> |
| 23 | 23 | |
| 24 | −#include <pthread.h> | |
| 25 | −#include <semaphore.h> | |
| 26 | − | |
| 27 | 24 | extern "C" { |
| 28 | 25 | #include "config.h" |
| 29 | 26 | #include "libavformat/avformat.h" |
| @@ -24,9 +24,6 @@ using std::atomic; · 23 unmodified lines | ||
| 24 | 24 | |
| 25 | 25 | #include <DeckLinkAPI.h> |
| 26 | 26 | |
| 27 | −#include <pthread.h> | |
| 28 | −#include <semaphore.h> | |
| 29 | − | |
| 30 | 27 | extern "C" { |
| 31 | 28 | #include "libavformat/avformat.h" |
| 32 | 29 | #include "libavformat/internal.h" |
| @@ -91,7 +88,10 @@ public: · 58 unmodified lines | ||
| 91 | 88 | |
| 92 | 89 | av_frame_unref(avframe); |
| 93 | 90 | |
| 94 | − sem_post(&ctx->semaphore); | |
| 91 | + pthread_mutex_lock(&ctx->mutex); | |
| 92 | + ctx->frames_buffer_available_spots++; | |
| 93 | + pthread_cond_broadcast(&ctx->cond); | |
| 94 | + pthread_mutex_unlock(&ctx->mutex); | |
| 95 | 95 | |
| 96 | 96 | return S_OK; |
| 97 | 97 | } |
| @@ -133,7 +133,6 @@ static int decklink_setup_video(AVFormatContext *avctx, AVStream *st) · 35 unmodified lines | ||
| 133 | 133 | ctx->output_callback = new decklink_output_callback(); |
| 134 | 134 | ctx->dlo->SetScheduledFrameCompletionCallback(ctx->output_callback); |
| 135 | 135 | |
| 136 | − /* Start video semaphore. */ | |
| 137 | 136 | ctx->frames_preroll = st->time_base.den * ctx->preroll; |
| 138 | 137 | if (st->time_base.den > 1000) |
| 139 | 138 | ctx->frames_preroll /= 1000; |
| @@ -141,7 +140,9 @@ static int decklink_setup_video(AVFormatContext *avctx, AVStream *st) · 1 unmodified line | ||
| 141 | 140 | /* Buffer twice as many frames as the preroll. */ |
| 142 | 141 | ctx->frames_buffer = ctx->frames_preroll * 2; |
| 143 | 142 | ctx->frames_buffer = FFMIN(ctx->frames_buffer, 60); |
| 144 | − sem_init(&ctx->semaphore, 0, ctx->frames_buffer); | |
| 143 | + pthread_mutex_init(&ctx->mutex, NULL); | |
| 144 | + pthread_cond_init(&ctx->cond, NULL); | |
| 145 | + ctx->frames_buffer_available_spots = ctx->frames_buffer; | |
| 145 | 146 | |
| 146 | 147 | /* The device expects the framerate to be fixed. */ |
| 147 | 148 | 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) · 63 unmodified lines | ||
| 211 | 212 | if (ctx->output_callback) |
| 212 | 213 | delete ctx->output_callback; |
| 213 | 214 | |
| 214 | − sem_destroy(&ctx->semaphore); | |
| 215 | + pthread_mutex_destroy(&ctx->mutex); | |
| 216 | + pthread_cond_destroy(&ctx->cond); | |
| 215 | 217 | |
| 216 | 218 | av_freep(&cctx->ctx); |
| 217 | 219 | |
| @@ -247,7 +249,12 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt) · 29 unmodified lines | ||
| 247 | 249 | } |
| 248 | 250 | |
| 249 | 251 | /* Always keep at most one second of frames buffered. */ |
| 250 | − sem_wait(&ctx->semaphore); | |
| 252 | + pthread_mutex_lock(&ctx->mutex); | |
| 253 | + while (ctx->frames_buffer_available_spots == 0) { | |
| 254 | + pthread_cond_wait(&ctx->cond, &ctx->mutex); | |
| 255 | + } | |
| 256 | + ctx->frames_buffer_available_spots--; | |
| 257 | + pthread_mutex_unlock(&ctx->mutex); | |
| 251 | 258 | |
| 252 | 259 | /* Schedule frame for playback. */ |
| 253 | 260 | hr = ctx->dlo->ScheduleVideoFrame((struct IDeckLinkVideoFrame *) frame, |