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[79.124.17.100]) by mx.google.com with ESMTP id de57si14009873ejc.156.2021.12.13.08.40.15; Mon, 13 Dec 2021 08:40:15 -0800 (PST) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5621D68AFEC; Mon, 13 Dec 2021 18:40:04 +0200 (EET) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-qt1-f182.google.com (mail-qt1-f182.google.com [209.85.160.182]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 90A1C68AF13 for ; Mon, 13 Dec 2021 18:40:02 +0200 (EET) Received: by mail-qt1-f182.google.com with SMTP id z9so15727824qtj.9 for ; Mon, 13 Dec 2021 08:40:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:content-transfer-encoding:mime-version :subject:message-id:date:to; bh=fzqlf1LB03t06XTdToSIBmP2iThOdFh+EGfV1tdEm00=; b=N3SSTA7R8gtP1Uw95nWZasmI0vu7+D0drGoyPbm9e2p81ee/PveMNiLadg5LVcP1Ay m1aBeypWnQQEQEZoW9t+B4tOlfgiPECRXN2Srdi/jQY1UPS7tR07QwxtoS8fA+BMoGXB x9pKipyCwnGftoLIjk3ob0shqjf5jV5XGAqOIVttDa5pQUr5EWvPmFBlxOI92PIrE+x7 4Ub/HkHgbgnfPHfuUZCk36Qk3dugnzRhUNBRpHlMVHD7ugPQQ++gj+hTpp9HWd4fiiyT SdvQpnPVxESxIx0BZfk5Uwj8WAUhI9bl9gDV+ZPmWEFFq3YdE1+i5VSzK3h3MWsXEUSW 83rA== X-Gm-Message-State: AOAM531703PbpcGuOX6IfA3OknidodlZ/9cYbcnwbZA1H9Sen/gAfuAI tv/7pAclgmI988LvIqaKK6MZ9FWqMEw= X-Received: by 2002:a05:622a:49:: with SMTP id y9mr46442054qtw.529.1639413600317; Mon, 13 Dec 2021 08:40:00 -0800 (PST) Received: from smtpclient.apple ([172.58.129.176]) by smtp.gmail.com with ESMTPSA id bm25sm6277781qkb.4.2021.12.13.08.39.59 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 Dec 2021 08:39:59 -0800 (PST) From: Romain Beauxis Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\)) Message-Id: <1299D3A3-E37C-4EE2-9F00-BCBA46FAD441@rastageeks.org> Date: Mon, 13 Dec 2021 10:39:58 -0600 To: ffmpeg-devel@ffmpeg.org X-Mailer: Apple Mail (2.3654.100.0.2.22) Subject: [FFmpeg-devel] [PATCH v2 02/03] libavdevice/avfoundation.m: Replace mutex-based concurrency handling in avfoundation.m by a thread-safe fifo queue with maximum length. X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" X-TUID: gY/T1Vj2MC3S This is the second patch of a series of 3 that cleanup and enhance the avfoundation implementation for libavdevice. This patch fixes the concurrency model. Avfoundation runs its own producing thread to send produced frames and ffmpeg runs its own thread to consume them. The existing implementation stores the last transmitted frame and uses a mutex to avoid concurrent access. However, this leads to situations where upcoming frames can be dropped if the ffmpeg thread is acessing the latest frame. This happens even when the thread would otherwise catch up and process frames fast enought. This patches changes this implementation to use a buffer queue with a max queue length and encapsulated thread-safety. This greatly simplifies the logic of the calling code and gives the consuming thread a chance to process all frames concurrently to the producing thread while avoiding memory leaks. Signed-off-by: Romain Beauxis --- libavdevice/avfoundation.m | 220 +++++++++++++++++++++---------------- 1 file changed, 127 insertions(+), 93 deletions(-) diff --git a/libavdevice/avfoundation.m b/libavdevice/avfoundation.m index 79c9207cfa..95414fd16a 100644 --- a/libavdevice/avfoundation.m +++ b/libavdevice/avfoundation.m @@ -26,7 +26,6 @@ */ #import -#include #include "libavutil/channel_layout.h" #include "libavutil/pixdesc.h" @@ -80,13 +79,97 @@ { AV_PIX_FMT_NONE, 0 } }; +#define MAX_QUEUED_OBJECTS 10 + +@interface AvdeviceAvfoundationBuffer : NSObject ++ (AvdeviceAvfoundationBuffer *) fromCMSampleBufferRef:(CMSampleBufferRef)sampleBuffer; +- (CMSampleBufferRef) getCMSampleBuffer; +@end + +@implementation AvdeviceAvfoundationBuffer { + CMSampleBufferRef sampleBuffer; +} + ++ (AvdeviceAvfoundationBuffer *) fromCMSampleBufferRef:(CMSampleBufferRef)sampleBuffer { + return [[AvdeviceAvfoundationBuffer alloc] init:sampleBuffer]; +} + +- (id) init:(CMSampleBufferRef)buffer { + sampleBuffer = buffer; + return self; +} + +- (CMSampleBufferRef) getCMSampleBuffer { + return sampleBuffer; +} +@end + +@interface AvdeviceAvfoundationBufferQueue : NSObject +- (CMSampleBufferRef) dequeue; +- (NSUInteger) count; +- (void) enqueue:(CMSampleBufferRef)obj; +@end + +@implementation AvdeviceAvfoundationBufferQueue { + NSLock *mutex; + NSMutableArray *queue; +} + +- (id) init { + mutex = [[[NSLock alloc] init] retain]; + queue = [[[NSMutableArray alloc] init] retain]; + return self; +} + +- (oneway void) release { + NSEnumerator *enumerator = [queue objectEnumerator]; + AvdeviceAvfoundationBuffer *buffer; + + while (buffer = [enumerator nextObject]) { + CFRelease([buffer getCMSampleBuffer]); + } + + [mutex release]; + [queue release]; +} + +- (NSUInteger) count { + [mutex lock]; + NSUInteger c = [queue count]; + [mutex unlock]; + return c; +} + +- (CMSampleBufferRef) dequeue { + [mutex lock]; + + if ([queue count] < 1) { + [mutex unlock]; + return nil; + } + + AvdeviceAvfoundationBuffer *buffer = [queue objectAtIndex:0]; + CMSampleBufferRef sampleBuffer = [buffer getCMSampleBuffer]; + [queue removeObjectAtIndex:0]; + [mutex unlock]; + + return sampleBuffer; +} + +- (void) enqueue:(CMSampleBufferRef)buffer { + [mutex lock]; + while (MAX_QUEUED_OBJECTS < [queue count]) { + [queue removeObjectAtIndex:0]; + } + [queue addObject:[AvdeviceAvfoundationBuffer fromCMSampleBufferRef:(CMSampleBufferRef)CFRetain(buffer)]]; + [mutex unlock]; +} +@end + typedef struct { AVClass* class; - int frames_captured; - int audio_frames_captured; - pthread_mutex_t frame_lock; id avf_delegate; id avf_audio_delegate; @@ -121,8 +204,8 @@ AVCaptureSession *capture_session; AVCaptureVideoDataOutput *video_output; AVCaptureAudioDataOutput *audio_output; - CMSampleBufferRef current_frame; - CMSampleBufferRef current_audio_frame; + AvdeviceAvfoundationBufferQueue *audio_frames; + AvdeviceAvfoundationBufferQueue *video_frames; AVCaptureDevice *observed_device; #if !TARGET_OS_IPHONE && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070 @@ -131,16 +214,6 @@ int observed_quit; } AVFContext; -static void lock_frames(AVFContext* ctx) -{ - pthread_mutex_lock(&ctx->frame_lock); -} - -static void unlock_frames(AVFContext* ctx) -{ - pthread_mutex_unlock(&ctx->frame_lock); -} - /** FrameReciever class - delegate for AVCaptureSession */ @interface AVFFrameReceiver : NSObject @@ -218,17 +291,7 @@ - (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)videoFrame fromConnection:(AVCaptureConnection *)connection { - lock_frames(_context); - - if (_context->current_frame != nil) { - CFRelease(_context->current_frame); - } - - _context->current_frame = (CMSampleBufferRef)CFRetain(videoFrame); - - unlock_frames(_context); - - ++_context->frames_captured; + [_context->video_frames enqueue:videoFrame]; } @end @@ -262,17 +325,7 @@ - (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)audioFrame fromConnection:(AVCaptureConnection *)connection { - lock_frames(_context); - - if (_context->current_audio_frame != nil) { - CFRelease(_context->current_audio_frame); - } - - _context->current_audio_frame = (CMSampleBufferRef)CFRetain(audioFrame); - - unlock_frames(_context); - - ++_context->audio_frames_captured; + [_context->audio_frames enqueue:audioFrame]; } @end @@ -284,12 +337,16 @@ static void destroy_context(AVFContext* ctx) [ctx->capture_session release]; [ctx->video_output release]; [ctx->audio_output release]; + [ctx->video_frames release]; + [ctx->audio_frames release]; [ctx->avf_delegate release]; [ctx->avf_audio_delegate release]; ctx->capture_session = NULL; ctx->video_output = NULL; ctx->audio_output = NULL; + ctx->video_frames = NULL; + ctx->audio_frames = NULL; ctx->avf_delegate = NULL; ctx->avf_audio_delegate = NULL; @@ -297,12 +354,6 @@ static void destroy_context(AVFContext* ctx) AudioConverterDispose(ctx->audio_converter); ctx->audio_converter = NULL; } - - pthread_mutex_destroy(&ctx->frame_lock); - - if (ctx->current_frame) { - CFRelease(ctx->current_frame); - } } static void parse_device_name(AVFormatContext *s) @@ -630,18 +681,18 @@ static int get_video_config(AVFormatContext *s) } // Take stream info from the first frame. - while (ctx->frames_captured < 1) { + while ([ctx->video_frames count] < 1) { CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, YES); } - lock_frames(ctx); + CMSampleBufferRef frame = [ctx->video_frames dequeue]; ctx->video_stream_index = stream->index; avpriv_set_pts_info(stream, 64, 1, avf_time_base); - image_buffer = CMSampleBufferGetImageBuffer(ctx->current_frame); - block_buffer = CMSampleBufferGetDataBuffer(ctx->current_frame); + image_buffer = CMSampleBufferGetImageBuffer(frame); + block_buffer = CMSampleBufferGetDataBuffer(frame); if (image_buffer) { image_buffer_size = CVImageBufferGetEncodedSize(image_buffer); @@ -657,10 +708,7 @@ static int get_video_config(AVFormatContext *s) stream->codecpar->format = ctx->pixel_format; } - CFRelease(ctx->current_frame); - ctx->current_frame = nil; - - unlock_frames(ctx); + CFRelease(frame); return 0; } @@ -680,27 +728,27 @@ static int get_audio_config(AVFormatContext *s) } // Take stream info from the first frame. - while (ctx->audio_frames_captured < 1) { + while ([ctx->audio_frames count] < 1) { CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, YES); } - lock_frames(ctx); + CMSampleBufferRef frame = [ctx->audio_frames dequeue]; ctx->audio_stream_index = stream->index; avpriv_set_pts_info(stream, 64, 1, avf_time_base); - format_desc = CMSampleBufferGetFormatDescription(ctx->current_audio_frame); + format_desc = CMSampleBufferGetFormatDescription(frame); const AudioStreamBasicDescription *input_format = CMAudioFormatDescriptionGetStreamBasicDescription(format_desc); if (!input_format) { - unlock_frames(ctx); + CFRelease(frame); av_log(s, AV_LOG_ERROR, "audio format not available\n"); return 1; } if (input_format->mFormatID != kAudioFormatLinearPCM) { - unlock_frames(ctx); + CFRelease(frame); av_log(s, AV_LOG_ERROR, "only PCM audio format are supported at the moment\n"); return 1; } @@ -778,16 +826,13 @@ static int get_audio_config(AVFormatContext *s) if (must_convert) { OSStatus ret = AudioConverterNew(input_format, &output_format, &ctx->audio_converter); if (ret != noErr) { - unlock_frames(ctx); + CFRelease(frame); av_log(s, AV_LOG_ERROR, "Error while allocating audio converter\n"); return 1; } } - CFRelease(ctx->current_audio_frame); - ctx->current_audio_frame = nil; - - unlock_frames(ctx); + CFRelease(frame); return 0; } @@ -805,8 +850,6 @@ static int avf_read_header(AVFormatContext *s) ctx->num_video_devices = [devices count] + [devices_muxed count]; - pthread_mutex_init(&ctx->frame_lock, NULL); - #if !TARGET_OS_IPHONE && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070 CGGetActiveDisplayList(0, NULL, &num_screens); #endif @@ -1006,6 +1049,8 @@ static int avf_read_header(AVFormatContext *s) // Initialize capture session ctx->capture_session = [[AVCaptureSession alloc] init]; + ctx->video_frames = [[AvdeviceAvfoundationBufferQueue alloc] init]; + ctx->audio_frames = [[AvdeviceAvfoundationBufferQueue alloc] init]; if (video_device && add_video_device(s, video_device)) { goto fail; @@ -1088,35 +1133,31 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) AVFContext* ctx = (AVFContext*)s->priv_data; do { - CVImageBufferRef image_buffer; - CMBlockBufferRef block_buffer; - lock_frames(ctx); - - if (ctx->current_frame != nil) { + if (1 <= [ctx->video_frames count]) { int status; int length = 0; - - image_buffer = CMSampleBufferGetImageBuffer(ctx->current_frame); - block_buffer = CMSampleBufferGetDataBuffer(ctx->current_frame); + CMSampleBufferRef video_frame = [ctx->video_frames dequeue]; + CVImageBufferRef image_buffer = CMSampleBufferGetImageBuffer(video_frame);; + CMBlockBufferRef block_buffer = CMSampleBufferGetDataBuffer(video_frame); if (image_buffer != nil) { length = (int)CVPixelBufferGetDataSize(image_buffer); } else if (block_buffer != nil) { length = (int)CMBlockBufferGetDataLength(block_buffer); } else { - unlock_frames(ctx); + CFRelease(video_frame); return AVERROR(EINVAL); } if (av_new_packet(pkt, length) < 0) { - unlock_frames(ctx); + CFRelease(video_frame); return AVERROR(EIO); } CMItemCount count; CMSampleTimingInfo timing_info; - if (CMSampleBufferGetOutputSampleTimingInfoArray(ctx->current_frame, 1, &timing_info, &count) == noErr) { + if (CMSampleBufferGetOutputSampleTimingInfoArray(video_frame, 1, &timing_info, &count) == noErr) { AVRational timebase_q = av_make_q(1, timing_info.presentationTimeStamp.timescale); pkt->pts = pkt->dts = av_rescale_q(timing_info.presentationTimeStamp.value, timebase_q, avf_time_base_q); } @@ -1133,15 +1174,14 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) status = AVERROR(EIO); } } - CFRelease(ctx->current_frame); - ctx->current_frame = nil; + CFRelease(video_frame); if (status < 0) { - unlock_frames(ctx); return status; } - } else if (ctx->current_audio_frame != nil) { - CMBlockBufferRef block_buffer = CMSampleBufferGetDataBuffer(ctx->current_audio_frame); + } else if (1 <= [ctx->audio_frames count]) { + CMSampleBufferRef audio_frame = [ctx->audio_frames dequeue]; + CMBlockBufferRef block_buffer = CMSampleBufferGetDataBuffer(audio_frame); size_t input_size = CMBlockBufferGetDataLength(block_buffer); int buffer_size = input_size / ctx->audio_buffers; @@ -1151,12 +1191,12 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) UInt32 size = sizeof(output_size); ret = AudioConverterGetProperty(ctx->audio_converter, kAudioConverterPropertyCalculateOutputBufferSize, &size, &output_size); if (ret != noErr) { - unlock_frames(ctx); + CFRelease(audio_frame); return AVERROR(EIO); } if (av_new_packet(pkt, output_size) < 0) { - unlock_frames(ctx); + CFRelease(audio_frame); return AVERROR(EIO); } @@ -1173,7 +1213,7 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) if (ret != kCMBlockBufferNoErr) { av_free(input_buffer); - unlock_frames(ctx); + CFRelease(audio_frame); return AVERROR(EIO); } } @@ -1191,7 +1231,7 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) av_free(input_buffer); if (ret != noErr) { - unlock_frames(ctx); + CFRelease(audio_frame); return AVERROR(EIO); } @@ -1199,7 +1239,7 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) } else { ret = CMBlockBufferCopyDataBytes(block_buffer, 0, pkt->size, pkt->data); if (ret != kCMBlockBufferNoErr) { - unlock_frames(ctx); + CFRelease(audio_frame); return AVERROR(EIO); } } @@ -1207,7 +1247,7 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) CMItemCount count; CMSampleTimingInfo timing_info; - if (CMSampleBufferGetOutputSampleTimingInfoArray(ctx->current_audio_frame, 1, &timing_info, &count) == noErr) { + if (CMSampleBufferGetOutputSampleTimingInfoArray(audio_frame, 1, &timing_info, &count) == noErr) { AVRational timebase_q = av_make_q(1, timing_info.presentationTimeStamp.timescale); pkt->pts = pkt->dts = av_rescale_q(timing_info.presentationTimeStamp.value, timebase_q, avf_time_base_q); } @@ -1215,21 +1255,15 @@ static int avf_read_packet(AVFormatContext *s, AVPacket *pkt) pkt->stream_index = ctx->audio_stream_index; pkt->flags |= AV_PKT_FLAG_KEY; - CFRelease(ctx->current_audio_frame); - ctx->current_audio_frame = nil; - - unlock_frames(ctx); + CFRelease(audio_frame); } else { pkt->data = NULL; - unlock_frames(ctx); if (ctx->observed_quit) { return AVERROR_EOF; } else { return AVERROR(EAGAIN); } } - - unlock_frames(ctx); } while (!pkt->data); return 0;