- 解码出的YUV数据要转成RGB数据然后显示，我使用AVFilter进行转换而不是sws_scale
- (void)viewDidLoad {
[super viewDidLoad];
// Do view setup here.
videoIndex = NSNotFound;
[self initDecoder]; //初始化解码器
[self initFilters]; //初始化过滤器
self.view.frame = NSRectFromCGRect(CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y, pCodecCtx->width, pCodecCtx->height));
timer = [NSTimer timerWithTimeInterval:1/fps repeats:YES block:^(NSTimer * _Nonnull timer) { //根据视频的fps解码渲染视频
[self decodeVideo]; //解码视频并渲染
[self.view setNeedsLayout:YES]; //刷新界面防止画面撕裂
}];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSEventTrackingRunLoopMode]; //在改变尺寸时保证计时器能调用
}
初始化解码器
- (void)initDecoder {
//av_register_all(); FFmpeg 4.0废弃
NSString * videoPath = [[NSBundle mainBundle] pathForResource:@"1" ofType:@"mp4"];
pFormatCtx = avformat_alloc_context();
if ((avformat_open_input(&pFormatCtx, videoPath.UTF8String, NULL, NULL)) != 0) {
NSLog(@"Could not open input stream");
return;
}
if ((avformat_find_stream_info(pFormatCtx, NULL)) < 0) {
NSLog(@"Could not find stream information");
return;
}
for (NSInteger i = 0; i < pFormatCtx->nb_streams; i++) {
if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
videoIndex = i; //视频流的索引
videoDuration = pFormatCtx->streams[i]->duration * av_q2d(pFormatCtx->streams[i]->time_base); //计算视频时长
_totalTimeLabel.stringValue = [NSString stringWithFormat:@"%.2ld:%.2ld", videoDuration/60, videoDuration%60];
if (pFormatCtx->streams[i]->avg_frame_rate.den && pFormatCtx->streams[i]->avg_frame_rate.num) {
fps = av_q2d(pFormatCtx->streams[i]->avg_frame_rate); //计算视频fps
} else {
fps = 30;
}
break;
}
}
if (videoIndex == NSNotFound) {
NSLog(@"Did not find a video stream");
return;
}
// FFmpeg 3.1 以上AVStream::codec被替换为AVStream::codecpar
pCodec = avcodec_find_decoder(pFormatCtx->streams[videoIndex]->codecpar->codec_id);
pCodecCtx = avcodec_alloc_context3(pCodec);
avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoIndex]->codecpar);
if (pCodec == NULL) {
NSLog(@"Could not open codec");
return;
}
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
NSLog(@"Could not open codec");
return;
}
av_dump_format(pFormatCtx, 0, videoPath.UTF8String, 0);
}
初始化过滤器
- (void)initFilters {
// avfilter_register_all(); //FFmpeg 4.0废弃
char args[512];
AVFilterInOut * inputs = avfilter_inout_alloc();
AVFilterInOut * outputs = avfilter_inout_alloc();
AVFilterGraph * filterGraph = avfilter_graph_alloc();
const AVFilter * buffer = avfilter_get_by_name("buffer");
const AVFilter * bufferSink = avfilter_get_by_name("buffersink");
if (!buffer || !bufferSink) {
NSLog(@"filter not found");
return;
}
AVRational time_base = pFormatCtx->streams[videoIndex]->time_base;
//视频的描述字符串，这些属性都是必须的否则会创建失败
snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d", pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,
time_base.num, time_base.den,pCodecCtx->sample_aspect_ratio.num,pCodecCtx->sample_aspect_ratio.den);
NSInteger ret = avfilter_graph_create_filter(&buffer_ctx, buffer, "in", args, NULL, filterGraph);
if (ret < 0) {
NSLog(@"can not create buffer source");
return;
}
ret = avfilter_graph_create_filter(&bufferSink_ctx, bufferSink, "out", NULL, NULL, filterGraph);
if (ret < 0) {
NSLog(@"can not create buffer sink");
return;
}
enum AVPixelFormat format[] = {AV_PIX_FMT_RGB24}; //想要转换的格式
ret = av_opt_set_bin(bufferSink_ctx, "pix_fmts", (uint8_t *)&format, sizeof(AV_PIX_FMT_RGB24), AV_OPT_SEARCH_CHILDREN);
if (ret < 0) {
NSLog(@"set bin error");
return;
}
outputs->name = av_strdup("in");
outputs->filter_ctx = buffer_ctx;
outputs->pad_idx = 0;
outputs->next = NULL;
inputs->name = av_strdup("out");
inputs->filter_ctx = bufferSink_ctx;
inputs->pad_idx = 0;
inputs->next = NULL;
ret = avfilter_graph_parse_ptr(filterGraph, "null", &inputs, &outputs, NULL); //只转换格式filter名称输入null
if (ret < 0) {
NSLog(@"parse error");
return;
}
ret = avfilter_graph_config(filterGraph, NULL);
if (ret < 0) {
NSLog(@"config error");
return;
}
avfilter_inout_free(&inputs);
avfilter_inout_free(&outputs);
}
解码并渲染视频
- (void)decodeVideo {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ //在全局队列中解码
AVPacket * packet = av_packet_alloc();
if (av_read_frame(self->pFormatCtx, packet) >= 0) {
if (packet->stream_index == self->videoIndex) { //解码视频流
//FFmpeg 3.0之后avcodec_send_packet和avcodec_receive_frame成对出现用于解码，包括音频和视频的解码，avcodec_decode_video2和avcodec_decode_audio4被废弃
NSInteger ret = avcodec_send_packet(self->pCodecCtx, packet);
if (ret < 0) {
NSLog(@"send packet error");
av_packet_free(&packet);
return;
}
AVFrame * frame = av_frame_alloc();
ret = avcodec_receive_frame(self->pCodecCtx, frame);
if (ret < 0) {
NSLog(@"receive frame error");
av_frame_free(&frame);
return;
}
//把解码出的frame传入filter中进行格式转换
ret = av_buffersrc_add_frame_flags(self->buffer_ctx, frame, 0);
if (ret < 0) {
NSLog(@"add frame error");
return;
}
//将转换好的rgbFrame取出来
AVFrame * rgbFrame = av_frame_alloc();
ret = av_buffersink_get_frame(self->bufferSink_ctx, rgbFrame);
if (ret < 0) {
NSLog(@"get frame error");
return;
}
/*
frame中data存放解码出的yuv数据，data[0]中是y数据，data[1]中是u数据，data[2]中是v数据，linesize对应的数据长度
rgb数据全部都存放在frame的data[0]中
*/
float time = packet->pts * av_q2d(self->pFormatCtx->streams[self->videoIndex]->time_base); //计算当前帧时间
av_packet_free(&packet);
av_frame_free(&frame);
//将frame中的RGB数据转成NSImage显示
CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, rgbFrame->data[0], rgbFrame->linesize[0] * self->pCodecCtx->height, kCFAllocatorNull);
if (CFDataGetLength(data) != 0) {
CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef cgImage = CGImageCreate(self->pCodecCtx->width, self->pCodecCtx->height, 8, 24, rgbFrame->linesize[0], colorSpace, bitmapInfo, provider, NULL, YES, kCGRenderingIntentDefault);
NSImage * image = [[NSImage alloc] initWithCGImage:cgImage size:NSSizeFromCGSize(CGSizeMake(self->pCodecCtx->width, self->pCodecCtx->height))];
CGImageRelease(cgImage);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
av_frame_free(&rgbFrame);
dispatch_async(dispatch_get_main_queue(), ^{
self.label.stringValue = [NSString stringWithFormat:@"%.2d:%.2d", (int)time/60, (int)time%60];
self.imageView.image = image;
self.slider.floatValue = time / (float)self->videoDuration;
});
}
}
} else {
avcodec_free_context(&self->pCodecCtx);
avformat_close_input(&self->pFormatCtx);
avformat_free_context(self->pFormatCtx);
[self->timer invalidate];
}
});
}
播放画面.png
虽然能播放视频但是有一个问题，根据视频的FPS调用定时器解码显示视频帧率并不能达到视频的帧率，因为解码，转换格式，合成图片这些操作费时，而且CPU占用率也很高，这些问题后面会解决。
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