Golang C.av_frame_alloc函數代碼示例

func NewFrame() (*Frame, error) {
	cFrame := C.av_frame_alloc()
	if cFrame == nil {
		return nil, ErrAllocationError
	}
	return NewFrameFromC(unsafe.Pointer(cFrame)), nil
}

// @todo should be private
func (this *Packet) Decode(cc *CodecCtx) (*Frame, bool, int, error) {
	var gotOutput int
	var ret int = 0

	if frames[cc.Type()] == nil {
		frames[cc.Type()] = &Frame{avFrame: C.av_frame_alloc(), mediaType: cc.Type()}
	}

	switch cc.Type() {
	case AVMEDIA_TYPE_AUDIO:
		ret = int(C.avcodec_decode_audio4(cc.avCodecCtx, frames[AVMEDIA_TYPE_AUDIO].avFrame, (*C.int)(unsafe.Pointer(&gotOutput)), &this.avPacket))
		if ret < 0 {
			return nil, false, int(ret), errors.New(fmt.Sprintf("Unable to decode audio packet, averror: %s", AvError(int(ret))))
		}

		break

	case AVMEDIA_TYPE_VIDEO:
		ret = int(C.avcodec_decode_video2(cc.avCodecCtx, frames[AVMEDIA_TYPE_VIDEO].avFrame, (*C.int)(unsafe.Pointer(&gotOutput)), &this.avPacket))
		if ret < 0 {
			return nil, false, int(ret), errors.New(fmt.Sprintf("Unable to decode video packet, averror: %s", AvError(int(ret))))
		}

		break

	default:
		return nil, false, int(ret), errors.New(fmt.Sprintf("Unknown codec type: %v", cc.Type()))
	}

	return frames[cc.Type()], (gotOutput > 0), int(ret), nil
}

func NewCapture(driver, device string) (*Capture, error) {
	id := Capture{index: -1}
	id.context = C.avformat_alloc_context()
	if id.context == (*C.AVFormatContext)(null) {
		return nil, fmt.Errorf("allocate output format context failed")
	}
	_driver := C.CString(driver)
	defer C.free(unsafe.Pointer(_driver))
	ifmt := C.av_find_input_format(_driver)
	if ifmt == (*C.AVInputFormat)(null) {
		return nil, fmt.Errorf("cannot find input driver: %s", driver)
	}
	dev := C.CString(device)
	defer C.free(unsafe.Pointer(dev))
	if C.avformat_open_input(&(id.context), dev, ifmt, (**C.AVDictionary)(null)) < 0 {
		return nil, fmt.Errorf("cannot open device %s", device)
	}
	if C.avformat_find_stream_info(id.context, (**C.AVDictionary)(null)) < 0 {
		return nil, fmt.Errorf("cannot find stream information")
	}
	num := int(id.context.nb_streams)
	streams := (*[1 << 30]*C.AVStream)(unsafe.Pointer(id.context.streams))
	var deCtx *C.AVCodecContext
	for i := 0; i < num; i++ {
		if streams[i].codec.codec_type == C.AVMEDIA_TYPE_VIDEO {
			deCtx = streams[i].codec
			id.index = i
			break
		}
	}
	if id.index == -1 {
		return nil, fmt.Errorf("cannot find video stream")
	}
	codec := C.avcodec_find_decoder(deCtx.codec_id)
	if codec == (*C.AVCodec)(null) {
		return nil, fmt.Errorf("cannot find decode codec")
	}
	id.codec = C.avcodec_alloc_context3(codec)
	if C.avcodec_copy_context(id.codec, deCtx) != 0 {
		return nil, fmt.Errorf("cannot copy codec context")
	}
	if C.avcodec_open2(id.codec, codec, (**C.struct_AVDictionary)(null)) < 0 {
		return nil, fmt.Errorf("cannot open decode codec")
	}
	id.sws = C.sws_getContext(id.codec.width,
		id.codec.height,
		id.codec.pix_fmt,
		id.codec.width,
		id.codec.height,
		C.AV_PIX_FMT_YUV420P, C.SWS_BILINEAR, (*C.struct_SwsFilter)(null), (*C.struct_SwsFilter)(null), (*C.double)(null))
	id.frame = C.av_frame_alloc()
	return &id, nil
}

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
}

// @todo should be private
func (this *Packet) Decode(cc *CodecCtx) (*Frame, bool, int, error) {
	var gotOutput int
	var ret int = 0

	if frames[cc.Type()] == nil {
		frames[cc.Type()] = &Frame{avFrame: C.av_frame_alloc(), mediaType: cc.Type()}
	}

	switch cc.Type() {
	case AVMEDIA_TYPE_AUDIO:
		ret = int(C.avcodec_decode_audio4(cc.avCodecCtx, frames[AVMEDIA_TYPE_AUDIO].avFrame, (*C.int)(unsafe.Pointer(&gotOutput)), &this.avPacket))
		if ret < 0 {
			return nil, false, int(ret), errors.New(fmt.Sprintf("Unable to decode audio packet, averror: %s", AvError(int(ret))))
		}
		break

	case AVMEDIA_TYPE_VIDEO:
		ret = int(C.avcodec_decode_video2(cc.avCodecCtx, frames[AVMEDIA_TYPE_VIDEO].avFrame, (*C.int)(unsafe.Pointer(&gotOutput)), &this.avPacket))

		if ret < 0 {
			return nil, false, int(ret), errors.New(fmt.Sprintf("Unable to decode video packet, averror: %s", AvError(int(ret))))
		}

		break

	default:
		return nil, false, int(ret), errors.New(fmt.Sprintf("Unknown codec type: %v", cc.Type()))
	}

	defer func() {
		if r := recover(); r != nil {
			buf := make([]byte, 1<<16)
			runtime.Stack(buf, false)
			reason := fmt.Sprintf("%v: %s", r, buf)
			fmt.Println("Runtime failure, reason -> %s", reason)

		}
	}()

	return frames[cc.Type()], (gotOutput > 0), int(ret), nil
}

func (this *Packet) DecodeToNewFrame(cc *CodecCtx) (*Frame, bool, int, error) {
	f := &Frame{avFrame: C.av_frame_alloc(), mediaType: cc.Type()}
	return this.decode(cc, f)
}

func NewFrame() *Frame {
	return &Frame{avFrame: C.av_frame_alloc()}
}

// 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
}

//AVFrame * av_frame_alloc (void)
//Allocate an AVFrame and set its fields to default values.
func Av_frame_alloc() *AVFrame {
	return (*AVFrame)(unsafe.Pointer(C.av_frame_alloc()))
}

//Allocate an Frame and set its fields to default values.
func AvFrameAlloc() *Frame {
	return (*Frame)(unsafe.Pointer(C.av_frame_alloc()))
}

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.........