Golang C.av_read_frame函數代碼示例

func (id *Capture) Read(frame *C.AVFrame) error {
	if frame == (*C.AVFrame)(null) {
		return fmt.Errorf("buffer error")
	}
	pkt := C.AVPacket{}
	C.av_init_packet(&pkt)
	defer C.av_free_packet(&pkt)
	if C.av_read_frame(id.context, &pkt) < 0 {
		return fmt.Errorf("read frame error")
	}
	if int(pkt.stream_index) != id.index {
		return fmt.Errorf("not video frame")
	}
	got_frame := C.int(0)
	if C.avcodec_decode_video2(id.codec, id.frame, &got_frame, &pkt) < 0 {
		return fmt.Errorf("decode frame error")
	}
	if got_frame != 0 {
		if C.sws_scale(id.sws, (**C.uint8_t)(&(id.frame.data[0])), &id.frame.linesize[0], 0, id.codec.height, &frame.data[0], &frame.linesize[0]) >= 0 {
			return nil
		}
		return fmt.Errorf("scale error")
	}
	return fmt.Errorf("no frame out")
}

func (dpx *Demultiplexer) Start() {
	for true {
		dpx.Packet = new(C.AVPacket)
		C.av_init_packet(dpx.Packet)

		if C.av_read_frame(dpx.Ds.Ctx, dpx.Packet) >= 0 {
			C.av_dup_packet(dpx.Packet)
		} else {
			println("end of file reached, closing channels")
			for i := 0; i < len(*dpx.tracks); i++ {
				print("closing channel ")
				println(i)
				close((*dpx.tracks)[i].stream)
			}
			break
		}
		var re Packet

		re.Pts = int64(dpx.Packet.pts)
		re.Dts = int64(dpx.Packet.dts)
		re.Size = int(dpx.Packet.size)
		re.Data = make([]byte, re.Size)
		data := (*(*[1 << 30]byte)(unsafe.Pointer(dpx.Packet.data)))[0:dpx.Packet.size]
		for i := 0; i < re.Size; i++ {
			re.Data[i] = data[i]
		}
		re.Stream = int(dpx.Packet.stream_index)
		re.Flags = int(dpx.Packet.flags)
		re.Duration = int(dpx.Packet.duration)
		re.Pos = int64(dpx.Packet.pos)
		C.av_free_packet(dpx.Packet)
		(*dpx.tracks)[re.Stream].stream <- re
	}
	//re * Packet
}

func (ctx *Context) ReadFrame(pkt *avcodec.Packet) (bool, error) {
	cPkt := (*C.AVPacket)(unsafe.Pointer(&pkt.CAVPacket))
	code := C.av_read_frame(ctx.CAVFormatContext, cPkt)
	if code < 0 {
		if avutil.ErrorCode(code) == avutil.ErrorCodeEOF {
			return false, nil
		}
		return false, avutil.NewErrorFromCode(avutil.ErrorCode(code))
	}
	return true, nil
}

func (this *FmtCtx) GetNextPacket() *Packet {
	p := NewPacket()
	for {

		if ret := C.av_read_frame(this.avCtx, &p.avPacket); int(ret) < 0 {
			Release(p)
			return nil
		}

		return p
	}
}

func (g *Generator) NextFrame() (image.Image, int64, error) {
	img := image.NewRGBA(image.Rect(0, 0, g.Width, g.Height))
	frame := C.av_frame_alloc()
	var pkt C.struct_AVPacket
	var frameFinished C.int
	for C.av_read_frame(g.avfContext, &pkt) == 0 {
		if int(pkt.stream_index) != g.vStreamIndex {
			C.av_free_packet(&pkt)
			continue
		}
		if C.avcodec_decode_video2(g.avcContext, frame, &frameFinished, &pkt) <= 0 {
			C.av_free_packet(&pkt)
			return nil, 0, errors.New("can't decode frame")
		}
		C.av_free_packet(&pkt)
		if frameFinished == 0 {
			continue
		}
		ctx := C.sws_getContext(
			C.int(g.Width),
			C.int(g.Height),
			g.avcContext.pix_fmt,
			C.int(g.Width),
			C.int(g.Height),
			C.PIX_FMT_RGBA,
			C.SWS_BICUBIC,
			nil,
			nil,
			nil,
		)
		if ctx == nil {
			return nil, 0, errors.New("can't allocate scaling context")
		}
		srcSlice := (**C.uint8_t)(&frame.data[0])
		srcStride := (*C.int)(&frame.linesize[0])
		dst := (**C.uint8_t)(unsafe.Pointer(&img.Pix))
		dstStride := (*C.int)(unsafe.Pointer(&[1]int{img.Stride}))
		C.sws_scale(
			ctx,
			srcSlice,
			srcStride,
			C.int(0),
			g.avcContext.height,
			dst,
			dstStride,
		)
		break
	}
	timestamp := int64(C.av_frame_get_best_effort_timestamp(frame))
	return img, timestamp, nil
}

func (this *FmtCtx) GetNewPackets() chan *Packet {
	yield := make(chan *Packet)

	go func() {
		for {
			p := NewPacket()

			if ret := C.av_read_frame(this.avCtx, &p.avPacket); int(ret) < 0 {
				break
			}

			yield <- p
		}

		close(yield)
	}()

	return yield
}

func (file *MediaFile) StartDecoding() {
	for _, i := range file.DecodedStreams {
		go file.Streams[i].decode()
	}

	go func() {
	get_packets:
		for packet := range file.packets {
			if packet == nil {
				break get_packets
			}
			for _, i := range file.DecodedStreams {
				if packet.stream_index == C.int(i) {
					file.Streams[i].packets <- packet
					continue get_packets
				}
			}
			C.av_free_packet(packet)
		}
		for _, i := range file.DecodedStreams {
			file.Streams[i].packets <- nil
		}
	}()

	go func() {
		for {
			packet := new(C.AVPacket)
			C.av_init_packet(packet)
			if C.av_read_frame(file.fmtctx, packet) < 0 {
				// assume EOF
				file.packets <- nil
				return
			}
			file.packets <- packet
		}
	}()
}

func (dpx *Demultiplexer) ReadPacket(re *Packet) bool {
	dpx.Packet = new(C.AVPacket)

	C.av_init_packet(dpx.Packet)
	defer C.av_free_packet(dpx.Packet)
	if C.av_read_frame(dpx.Ds.Ctx, dpx.Packet) >= 0 {
		C.av_dup_packet(dpx.Packet)
	} else {
		return false
	}
	re.Pts = int64(dpx.Packet.pts)
	re.Dts = int64(dpx.Packet.dts)
	re.Size = int(dpx.Packet.size)
	re.Data = make([]byte, re.Size)
	data := (*(*[1 << 30]byte)(unsafe.Pointer(dpx.Packet.data)))[0:dpx.Packet.size]
	for i := 0; i < re.Size; i++ {
		re.Data[i] = data[i]
	}
	re.Stream = int(dpx.Packet.stream_index)
	re.Flags = int(dpx.Packet.flags)
	re.Duration = int(dpx.Packet.duration)
	re.Pos = int64(dpx.Packet.pos)
	return true
}

func av_read_frame(ctx *FormatContext, packet *AVPacket) int {
	return int(C.av_read_frame(ctx.ctx, (*C.AVPacket)(unsafe.Pointer(packet))))
}

func main() {

	var (
		fmt_ctx          *C.AVFormatContext
		video_stream_idx C.int
		pkt              C.AVPacket
		fn               string
	)
	flag.StringVar(&fn, "i", fn, "Input filename")
	flag.Parse()
	if fn == "" {
		flag.PrintDefaults()
		os.Exit(1)
	}
	cfn := C.CString(fn)
	defer C.free(unsafe.Pointer(cfn))
	C.av_register_all()
	if err := C.avformat_open_input(&fmt_ctx, cfn, nil, nil); err < 0 {
		log.Fatalf("Could not open source file %s, %d\n", fn, err)
	}
	// The smd codecs aren't too happy with missing PTS
	fmt_ctx.flags |= C.AVFMT_FLAG_GENPTS
	defer C.avformat_close_input(&fmt_ctx)
	if err := C.avformat_find_stream_info(fmt_ctx, nil); err < 0 {
		log.Fatalf("Could not find stream information: %d", err)
	}
	if err := open_codec_context(&video_stream_idx, fmt_ctx, C.AVMEDIA_TYPE_VIDEO); err < 0 {
		log.Fatalf("Could not open codec context: %d", err)
	}
	log.Printf("fmt_ctx: %+v", fmt_ctx)
	streams := (*[32]*C.AVStream)(unsafe.Pointer(fmt_ctx.streams))
	log.Printf("video stream codec: %+v", streams[video_stream_idx].codec.codec_id)

	log.Printf("time_base: %+v", streams[video_stream_idx].time_base)
	num := 1000000 * float64(streams[video_stream_idx].time_base.num)
	den := float64(streams[video_stream_idx].time_base.den)

	var codec C.ismd_codec_type_t
	switch vc := streams[video_stream_idx].codec.codec_id; vc {
	case C.AV_CODEC_ID_H264:
		codec = C.ISMD_CODEC_TYPE_H264
	case C.AV_CODEC_ID_MPEG1VIDEO:
		fallthrough
	case C.AV_CODEC_ID_MPEG2VIDEO:
		codec = C.ISMD_CODEC_TYPE_MPEG2
	case C.AV_CODEC_ID_MPEG4:
		codec = C.ISMD_CODEC_TYPE_MPEG4
	default:
		log.Fatalf("Unhandled video codec: %d", vc)
	}

	Init(codec, C.GDL_PLANE_ID_UPP_C)
	defer Destroy()

	C.av_init_packet(&pkt)
	pkt.data = nil
	pkt.size = 0

	running := true
	go func() {
		os.Stdin.Read(make([]byte, 1))
		running = false
	}()
	frame := 0
	for running && C.av_read_frame(fmt_ctx, &pkt) >= 0 {
		orig_pkt := pkt
		wrote := false
		for pkt.stream_index == video_stream_idx && (pkt.size > 0) {
			pts := num * float64(pkt.pts) / den
			WriteToInputPort(uintptr(unsafe.Pointer(pkt.data)), C.size_t(pkt.size), pts, 32*1024)
			wrote = true
			break
		}
		if wrote {
			frame++
			if frame%100 == 0 {
				var stat C.ismd_vidrend_stats_t
				C.ismd_vidrend_get_stats(m_video_render, &stat)
				log.Printf("%+v", stat)
			}
		}

		C.av_free_packet(&orig_pkt)
	}
}

//Return the next frame of a stream.
func (s *Context) AvReadFrame(pkt *avcodec.Packet) int {
	return int(C.av_read_frame((*C.struct_AVFormatContext)(unsafe.Pointer(s)), (*C.struct_AVPacket)(unsafe.Pointer(pkt))))
}

//int av_read_frame (AVFormatContext *s, AVPacket *pkt)
//Return the next frame of a stream.
func Av_read_frame(s *AVFormatContext, pkt *avcodec.AVPacket) int {
	return int(C.av_read_frame((*C.struct_AVFormatContext)(unsafe.Pointer(s)), (*C.struct_AVPacket)(unsafe.Pointer(pkt))))
}

// ImageWxH returns a screenshot at the ts milliseconds, scaled to the specified width and height.
func (g *Generator) ImageWxH(ts int64, width, height int) (image.Image, error) {
	img := image.NewRGBA(image.Rect(0, 0, width, height))
	frame := C.av_frame_alloc()
	defer C.av_frame_free(&frame)
	frameNum := C.av_rescale(
		C.int64_t(ts),
		C.int64_t(g.streams[g.vStreamIndex].time_base.den),
		C.int64_t(g.streams[g.vStreamIndex].time_base.num),
	) / 1000
	if C.avformat_seek_file(
		g.avfContext,
		C.int(g.vStreamIndex),
		0,
		frameNum,
		frameNum,
		C.AVSEEK_FLAG_FRAME,
	) < 0 {
		return nil, errors.New("can't seek to timestamp")
	}
	C.avcodec_flush_buffers(g.avcContext)
	var pkt C.struct_AVPacket
	var frameFinished C.int
	for C.av_read_frame(g.avfContext, &pkt) == 0 {
		if int(pkt.stream_index) != g.vStreamIndex {
			C.av_free_packet(&pkt)
			continue
		}
		if C.avcodec_decode_video2(g.avcContext, frame, &frameFinished, &pkt) <= 0 {
			C.av_free_packet(&pkt)
			return nil, errors.New("can't decode frame")
		}
		C.av_free_packet(&pkt)
		if frameFinished == 0 || pkt.dts < frameNum {
			continue
		}
		ctx := C.sws_getContext(
			C.int(g.Width),
			C.int(g.Height),
			g.avcContext.pix_fmt,
			C.int(width),
			C.int(height),
			C.PIX_FMT_RGBA,
			C.SWS_BICUBIC,
			nil,
			nil,
			nil,
		)
		if ctx == nil {
			return nil, errors.New("can't allocate scaling context")
		}
		srcSlice := (**C.uint8_t)(&frame.data[0])
		srcStride := (*C.int)(&frame.linesize[0])
		dst := (**C.uint8_t)(unsafe.Pointer(&img.Pix))
		dstStride := (*C.int)(unsafe.Pointer(&[1]int{img.Stride}))
		C.sws_scale(
			ctx,
			srcSlice,
			srcStride,
			0,
			g.avcContext.height,
			dst,
			dstStride,
		)
		break
	}
	return img, nil
}

func (self *Decoder) Start(videoStream, audioStream *C.AVStream,
	scaleWidth, scaleHeight C.int) *Decoder {

	self.running = true
	self.duration = time.Duration(self.FormatContext.duration * C.AV_TIME_BASE / 1000)
	vCodecCtx := videoStream.codec
	aCodecCtx := audioStream.codec

	self.durationPerSample = time.Second / time.Duration(aCodecCtx.sample_rate)

	// frame pool
	poolSize := 16
	pool := make(chan *C.AVFrame, poolSize)
	self.pool = pool
	numBytes := C.size_t(C.avpicture_get_size(C.PIX_FMT_YUV420P, scaleWidth, scaleHeight))
	for i := 0; i < poolSize; i++ {
		frame := C.av_frame_alloc()
		self.frames = append(self.frames, frame)
		buffer := (*C.uint8_t)(unsafe.Pointer(C.av_malloc(numBytes)))
		self.buffers = append(self.buffers, buffer)
		C.avpicture_fill((*C.AVPicture)(unsafe.Pointer(frame)), buffer, C.PIX_FMT_YUV420P,
			scaleWidth, scaleHeight)
		pool <- frame
	}

	// decode
	self.frameChan = make(chan *C.AVFrame, 512)
	go func() {
		runtime.LockOSThread()

		// scale context
		scaleContext := C.sws_getCachedContext(nil, vCodecCtx.width, vCodecCtx.height, vCodecCtx.pix_fmt,
			scaleWidth, scaleHeight, C.PIX_FMT_YUV420P, C.SWS_LANCZOS, nil, nil, nil)
		if scaleContext == nil {
			log.Fatal("get scale context failed")
		}

		// resample context
		resampleContext := C.swr_alloc_set_opts(nil,
			C.AV_CH_LAYOUT_STEREO, C.AV_SAMPLE_FMT_FLT, aCodecCtx.sample_rate,
			C.int64_t(aCodecCtx.channel_layout), aCodecCtx.sample_fmt, aCodecCtx.sample_rate,
			0, nil)
		if resampleContext == nil {
			log.Fatal("get resample context failed")
		}
		C.swr_init(resampleContext)

		var packet C.AVPacket
		var frameFinished C.int
		var pts int64
		var packetTime time.Duration
		vFrame := C.av_frame_alloc()
		aFrame := C.av_frame_alloc()
		videoIndex := videoStream.index
		audioIndex := audioStream.index
		resampleBuffer := (*C.uint8_t)(C.av_malloc(4096 * 8))
		resampleBufferp := &resampleBuffer

		self.Timer = NewTimer()

		// decode
		for self.running {

			// seek
			if self.seekTarget > 0 {
				if C.av_seek_frame(self.FormatContext, -1,
					C.int64_t(float64(self.seekNext)/float64(time.Second)*float64(C.AV_TIME_BASE)),
					C.AVSEEK_FLAG_BACKWARD) < 0 {
					log.Fatal("seek error")
				}
				for _, codecCtx := range self.openedCodecs {
					C.avcodec_flush_buffers(codecCtx)
				}
				p("frame seek done\n")
			}

		read_packet:
			// read packet
			C.av_free_packet(&packet)
			if C.av_read_frame(self.FormatContext, &packet) < 0 { // read packet
				log.Fatal("read frame error") //TODO stop gracefully
			}

			// get packet time
			if packet.dts != C.AV_NOPTS_VALUE {
				pts = int64(packet.dts)
			} else {
				pts = 0
			}
			if packet.stream_index == videoIndex {
				packetTime = time.Duration(float64(pts) * float64(C.av_q2d(videoStream.time_base)) * float64(time.Second))
			} else if packet.stream_index == audioIndex {
				packetTime = time.Duration(float64(pts) * float64(C.av_q2d(audioStream.time_base)) * float64(time.Second))
			} else { // ignore packet
				goto read_packet
			}
			p("packet time %v at timer time %v\n", packetTime, self.Timer.Now())

			// check seek
			if self.seekTarget > 0 && packetTime > 0 { // if packet time cannot determined, skip
//.........這裏部分代碼省略.........