`VENC` Module API Manual#

Overview#

This manual provides a detailed introduction to the K230_CanMV VENC module’s API. Developers can call these APIs to perform video encoding, generating streams with different resolutions and encoding formats. The VENC module must be used in conjunction with the camera module to implement encoding functionality.

API Introduction#

The VENC module provides the Encoder class, which includes the following methods:

Encoder.init#

Description

Constructor, used to initialize the decoder instance.

Syntax

encoder = Encoder()

Parameters

Parameter Name	Description	Input/Output
None

Return Value

Return Value	Description
Encoder object	Encoder object

`Encoder.SetOutBufs`#

Description

Configures the encoder’s output buffers.

Syntax

Encoder.SetOutBufs(chn, buf_num, width, height)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input
buf_num	Number of output buffers	Input
width	Encoding image width	Input
height	Encoding image height	Input

Return Value

Return Value	Description
None

Notes

Must be called before MediaManager.init()

`Encoder.Create`#

Description

Creates an encoder instance.

Syntax

Encoder.Create(chn, chnAttr)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input
chnAttr	Encoding channel attribute structure	Input

Return Value

Return Value	Description
None

Notes

VENC supports up to 4 encoding channels, with the encoding channel number ranging from [0, 3]. The 4th channel is fixed for IDE image transmission. Unless compress_for_ide is called, it is recommended to use only [0, 2].

`Encoder.Start`#

Description

Starts the encoding process.

Syntax

Encoder.Start(chn)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input

Return Value

Return Value	Description
None

`Encoder.SendFrame`#

Description

Sends image data to the encoder for encoding.

Syntax

Encoder.SendFrame(venc_chn, frame_info)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input
frame_info	Original image information structure	Input

Return Value

Return Value	Description
0	Success
Non-zero	Failure

Notes

A complete frame of data or a data stream of variable length can be encoded.

`Encoder.GetStream`#

Description

Gets one frame of encoded stream data.

Syntax

Encoder.GetStream(chn, streamData,timeout=-1)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input
streamData	Encoded stream structure	Output
timeout	Timeout for getting stream. Value range: [-1, +∞ ) -1: Blocking. 0: Non-blocking. Greater than 0: Timeout duration	Input

Return Value

Return Value	Description
0	Success
Non-zero	Failure

`Encoder.ReleaseStream`#

Description

Releases one frame of stream buffer.

Syntax

Encoder.ReleaseStream(chn, streamData)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input
streamData	Encoded stream structure	Input

Return Value

Return Value	Description
None

`Encoder.Stop`#

Description

Stops the encoding process.

Syntax

Encoder.Stop(chn)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input

Return Value

Return Value	Description
None

`Encoder.Destroy`#

Description

Destroys the encoder instance.

Syntax

Encoder.Destroy(chn)

Parameters

Parameter Name	Description	Input/Output
chn	Encoding channel number	Input

Return Value

Return Value	Description
None

Data Structure Description#

`ChnAttrStr`#

Description

Encoder channel attribute structure.

Definition

class ChnAttrStr:
    def __init__(self, payloadType, profile, picWidth, picHeight,bit_rate = 4000,gopLen = 30,src_frame_rate = 30,dst_frame_rate = 30,mjpeg_quality_factor = 45):
        self.payload_type = payloadType
        self.profile = profile
        self.pic_width = picWidth
        self.pic_height = picHeight
        self.gop_len = gopLen
        self.bit_rate = bit_rate
        self.src_frame_rate = src_frame_rate
        self.dst_frame_rate = dst_frame_rate
        self.mjpeg_quality_factor = mjpeg_quality_factor

Members

成员名称	描述
payload_type	Encoding format (h264/h265)
profile	Encoding Profile
pic_width	Image width
pic_height	Image height
gop_len	Encoding GOP length
bit_rate	Bit rate
src_frame_rate	Input frame rate
dst_frame_rate	Output frame rate
mjpeg_quality_factor	MJPEG encoding quality factor (image quality compression ratio parameter)

`StreamData`#

Description

Bitstream structure.

Definition

class StreamData:
    def __init__(self):
        self.data = [0 for i in range(0, VENC_PACK_CNT_MAX)]
        self.phy_addr = [0 for i in range(0, VENC_PACK_CNT_MAX)]
        self.data_size = [0 for i in range(0, VENC_PACK_CNT_MAX)]
        self.stream_type = [0 for i in range(0, VENC_PACK_CNT_MAX)]
        self.pts = [0 for i in range(0, VENC_PACK_CNT_MAX)]
        self.pack_cnt = 0

Members

成员名称	描述
data	Bitstream data address
phy_addr	Bitstream physical address
data_size	Bitstream data size
stream_type	Frame type
pts	Presentation timestamp
pack_cnt	Number of packs in the bitstream

Notes

VENC_PACK_CNT_MAX indicates the maximum number of packs in the bitstream structure, currently set to 12.

`payload_type`#

Description

Encoding format type.

Members

成员名称	描述
PAYLOAD_TYPE_H264	H.264 encoding format
PAYLOAD_TYPE_H265	H.265 encoding format

`profile`#

Description

Encoding Profile.

Members

成员名称	描述
H264_PROFILE_BASELINE	H.264 Baseline Profile
H264_PROFILE_MAIN	H.264 Main Profile
H264_PROFILE_HIGH	H.264 High Profile
H265_PROFILE_MAIN	H.265 Main Profile

`stream_type`#

Description

Bitstream frame type.

Members

成员名称	描述
STREAM_TYPE_HEADER	Bitstream Header
STREAM_TYPE_I	I frame
STREAM_TYPE_P	P frame

Example Programs#

Example 1#

Bind VENC to VICAP, and save the obtained encoded data to a file.

from media.vencoder import *
from media.sensor import *
from media.media import *
import time, os

def vi_bind_venc_test(file_name, width=1280, height=720):
    print("VENC 测试开始")
    venc_chn = VENC_CHN_ID_0
    width = ALIGN_UP(width, 16)
    venc_payload_type = K_PT_H264

    # 判断文件扩展名
    suffix = file_name.split('.')[-1]
    if suffix == '264':
        venc_payload_type = K_PT_H264
    elif suffix == '265':
        venc_payload_type = K_PT_H265
    else:
        print("未知文件扩展名")
        return

    # 初始化传感器
    sensor = Sensor()
    sensor.reset()
    sensor.set_framesize(width=width, height=height, alignment=12)
    sensor.set_pixformat(Sensor.YUV420SP)

    # 实例化视频编码器
    encoder = Encoder()
    encoder.SetOutBufs(venc_chn, 8, width, height)

    # 绑定camera和venc
    link = MediaManager.link(sensor.bind_info()['src'], (VIDEO_ENCODE_MOD_ID, VENC_DEV_ID, venc_chn))

    # init media manager
    MediaManager.init()

    if (venc_payload_type == K_PT_H264):
        chnAttr = ChnAttrStr(encoder.PAYLOAD_TYPE_H264, encoder.H264_PROFILE_MAIN, width, height)
    elif (venc_payload_type == K_PT_H265):
        chnAttr = ChnAttrStr(encoder.PAYLOAD_TYPE_H265, encoder.H265_PROFILE_MAIN, width, height)

    streamData = StreamData()

    # 创建编码器
    encoder.Create(venc_chn, chnAttr)

    # 开始编码
    encoder.Start(venc_chn)
    # 启动camera
    sensor.run()

    frame_count = 0
    print("save stream to file: ", file_name)

    with open(file_name, "wb") as fo:
        try:
            while True:
                os.exitpoint()
                encoder.GetStream(venc_chn, streamData) # 获取一帧码流

                for pack_idx in range(0, streamData.pack_cnt):
                    stream_data = uctypes.bytearray_at(streamData.data[pack_idx], streamData.data_size[pack_idx])
                    fo.write(stream_data) # 码流写文件
                    print("stream size: ", streamData.data_size[pack_idx], "stream type: ", streamData.stream_type[pack_idx])

                encoder.ReleaseStream(venc_chn, streamData) # 释放一帧码流

                frame_count += 1
                if frame_count >= 200:
                    break
        except KeyboardInterrupt as e:
            print("user stop: ", e)
        except BaseException as e:
            import sys
            sys.print_exception(e)

    # 停止camera
    sensor.stop()
    # 销毁camera和venc的绑定
    del link
    # 停止编码
    encoder.Stop(venc_chn)
    # 销毁编码器
    encoder.Destroy(venc_chn)
    # 清理buffer
    MediaManager.deinit()
    print("venc_test stop")

if __name__ == "__main__":
    os.exitpoint(os.EXITPOINT_ENABLE)
    vi_bind_venc_test("/sdcard/examples/test.264",800,480)  # vi绑定venc示例

Example 2#

Encode venc data stream and save it to a file.

from media.vencoder import *
from media.sensor import *
from media.media import *
import time, os

def stream_venc_test(file_name,width=1280, height=720):
    print("venc_test start")
    venc_chn = VENC_CHN_ID_0
    width = ALIGN_UP(width, 16)
    venc_payload_type = K_PT_H264

    # 判断文件类型
    suffix = file_name.split('.')[-1]
    if suffix == '264':
        venc_payload_type = K_PT_H264
    elif suffix == '265':
        venc_payload_type = K_PT_H265
    else:
        print("Unknown file extension")
        return

    # 初始化sensor
    sensor = Sensor()
    sensor.reset()
    # 设置camera 输出buffer
    # set chn0 output size
    sensor.set_framesize(width = width, height = height, alignment=12)
    # set chn0 output format
    sensor.set_pixformat(Sensor.YUV420SP)


    # 实例化video encoder
    encoder = Encoder()
    # 设置video encoder 输出buffer
    encoder.SetOutBufs(venc_chn, 8, width, height)

    # init media manager
    MediaManager.init()

    if (venc_payload_type == K_PT_H264):
        chnAttr = ChnAttrStr(encoder.PAYLOAD_TYPE_H264, encoder.H264_PROFILE_MAIN, width, height)
    elif (venc_payload_type == K_PT_H265):
        chnAttr = ChnAttrStr(encoder.PAYLOAD_TYPE_H265, encoder.H265_PROFILE_MAIN, width, height)

    streamData = StreamData()

    # 创建编码器
    encoder.Create(venc_chn, chnAttr)

    # 开始编码
    encoder.Start(venc_chn)
    # 启动camera
    sensor.run()

    frame_count = 0
    print("save stream to file: ", file_name)

    yuv420sp_img = None
    frame_info = k_video_frame_info()
    with open(file_name, "wb") as fo:
        try:
            while True:
                os.exitpoint()
                yuv420sp_img = sensor.snapshot(chn=CAM_CHN_ID_0)
                if (yuv420sp_img == -1):
                    continue

                frame_info.v_frame.width = yuv420sp_img.width()
                frame_info.v_frame.height = yuv420sp_img.height()
                frame_info.v_frame.pixel_format = Sensor.YUV420SP
                frame_info.pool_id = yuv420sp_img.poolid()
                frame_info.v_frame.phys_addr[0] = yuv420sp_img.phyaddr()
                #frame_info.v_frame.phys_addr[1] = yuv420sp_img.phyaddr(1)
                if (yuv420sp_img.width() == 800 and yuv420sp_img.height() == 480):
                    frame_info.v_frame.phys_addr[1] = frame_info.v_frame.phys_addr[0] + frame_info.v_frame.width*frame_info.v_frame.height + 1024
                elif (yuv420sp_img.width() == 1920 and yuv420sp_img.height() == 1080):
                    frame_info.v_frame.phys_addr[1] = frame_info.v_frame.phys_addr[0] + frame_info.v_frame.width*frame_info.v_frame.height + 3072
                elif (yuv420sp_img.width() == 640 and yuv420sp_img.height() == 360):
                    frame_info.v_frame.phys_addr[1] = frame_info.v_frame.phys_addr[0] + frame_info.v_frame.width*frame_info.v_frame.height + 3072
                else:
                    frame_info.v_frame.phys_addr[1] = frame_info.v_frame.phys_addr[0] + frame_info.v_frame.width*frame_info.v_frame.height


                encoder.SendFrame(venc_chn,frame_info)
                encoder.GetStream(venc_chn, streamData) # 获取一帧码流

                for pack_idx in range(0, streamData.pack_cnt):
                    stream_data = uctypes.bytearray_at(streamData.data[pack_idx], streamData.data_size[pack_idx])
                    fo.write(stream_data) # 码流写文件
                    print("stream size: ", streamData.data_size[pack_idx], "stream type: ", streamData.stream_type[pack_idx])

                encoder.ReleaseStream(venc_chn, streamData) # 释放一帧码流

                frame_count += 1
                if frame_count >= 200:
                    break
        except KeyboardInterrupt as e:
            print("user stop: ", e)
        except BaseException as e:
            import sys
            sys.print_exception(e)

    # 停止camera
    sensor.stop()
    # 停止编码
    encoder.Stop(venc_chn)
    # 销毁编码器
    encoder.Destroy(venc_chn)
    # 清理buffer
    MediaManager.deinit()
    print("venc_test stop")

if __name__ == "__main__":
    os.exitpoint(os.EXITPOINT_ENABLE)
    stream_venc_test("/sdcard/examples/test.264",800,480)  # venc编码数据流示例

VENC Module API Manual

Contents

`VENC` Module API Manual#

Overview#

API Introduction#

Encoder.init#

`Encoder.SetOutBufs`#

`Encoder.Create`#

`Encoder.Start`#

`Encoder.SendFrame`#

`Encoder.GetStream`#

`Encoder.ReleaseStream`#

`Encoder.Stop`#

`Encoder.Destroy`#

Data Structure Description#

`ChnAttrStr`#

`StreamData`#

`payload_type`#

`profile`#

`stream_type`#

Example Programs#

Example 1#

Example 2#

VENC Module API Manual

Contents

VENC Module API Manual#

Overview#

API Introduction#

Encoder.__init__#

Encoder.SetOutBufs#

Encoder.Create#

Encoder.Start#

Encoder.SendFrame#

Encoder.GetStream#

Encoder.ReleaseStream#

Encoder.Stop#

Encoder.Destroy#

Data Structure Description#

ChnAttrStr#

StreamData#

payload_type#

profile#

stream_type#

Example Programs#

Example 1#

Example 2#

`VENC` Module API Manual#

Encoder.init#

`Encoder.SetOutBufs`#

`Encoder.Create`#

`Encoder.Start`#

`Encoder.SendFrame`#

`Encoder.GetStream`#

`Encoder.ReleaseStream`#

`Encoder.Stop`#

`Encoder.Destroy`#

`ChnAttrStr`#

`StreamData`#

`payload_type`#

`profile`#

`stream_type`#