VDEC Module API Manual#
Overview#
This document provides a detailed introduction to the K230_CanMV VDEC module’s API. This module supports H.264 and H.265 decoding, and can be bound to the VO module to output the decoded data to the VO display device.
API Introduction#
This module provides the Decoder class, which contains the following methods:
Decoder.__init__#
Description
Constructor used to initialize a decoder instance.
Syntax
decoder = Decoder(type)
Parameters
Parameter Name |
Description |
Input/Output |
|---|---|---|
type |
Encoding type |
Input |
Return Value
Return Value |
Description |
|---|---|
Decoder object |
Decoder object |
Notes
The VDEC module supports up to four concurrent decodings.
Decoder.create#
Description
Create a decoder instance.
Syntax
Decoder.create()
Parameters
None
Return Value
Return Value |
Description |
|---|---|
None |
Decoder.destroy#
Description
Destroy a decoder instance.
Syntax
Decoder.destroy()
Parameters
None
Return Value
Return Value |
Description |
|---|---|
None |
Decoder.start#
Description
Start the decoder and begin the decoding process.
Syntax
Decoder.start()
Parameters
None
Return Value
Return Value |
Description |
|---|---|
None |
Decoder.decode#
Description
Decode one frame of data.
Syntax
Decoder.decode(stream_data)
Parameters
Parameter Name |
Description |
Input/Output |
|---|---|---|
stream_data |
Encoded data |
Input |
Return Value
Return Value |
Description |
|---|---|
None |
Decoder.stop#
Description
Release the stream buffer of the current decoded frame.
Syntax
Decoder.stop()
Parameters
None
Return Value
Return Value |
Description |
|---|---|
None |
Decoder.get_vdec_channel#
Description
Return the decoder output channel number.
Syntax
Decoder.get_vdec_channel()
Parameters
None
Return Value
Return Value |
Description |
|---|---|
chn |
Decoder output channel number |
Decoder.bind_info#
Description
Used when calling Display.bind_layer, to obtain binding information.
Syntax
Decoder.bind_info(x = 0, y = 0, width = 1920,height = 1080,pix_format=PIXEL_FORMAT_YUV_SEMIPLANAR_420,chn = 0)
Parameters
Parameter Name |
Description |
Input/Output |
|---|---|---|
x |
Horizontal starting coordinate of the binding area |
Input |
y |
Vertical starting coordinate of the binding area |
Input |
width |
Width of the decoded frame |
Input |
height |
Height of the decoded frame |
Input |
pix_format |
Image pixel format |
Input |
chn |
Decoder output channel number |
Input |
Return Value
Return Value |
Description |
|---|---|
dict object |
Contains the channel’s source information, area size, and pixel format |
Data Structure Description#
StreamData#
Description
Stream structure containing decoded data and its timestamp information.
Definition
class StreamData:
def __init__(self):
self.data
self.pts
Members
Member Name |
Description |
|---|---|
data |
Stream data |
pts |
Timestamp information |
Example Program#
Example 1#
from media.media import *
from mpp.payload_struct import *
import media.vdecoder as vdecoder
from media.display import *
import time
import os
STREAM_SIZE = 40960
def vdec_test(file_name, width=1280, height=720):
print("vdec_test start")
vdec_chn = VENC_CHN_ID_0
vdec_width = ALIGN_UP(width, 16)
vdec_height = height
vdec = None
vdec_payload_type = K_PT_H264
# display_type = Display.VIRT
display_type = Display.ST7701 # 使用 ST7701 LCD 屏幕作为输出，最大分辨率 800*480
# display_type = Display.LT9611 # 使用 HDMI 作为输出
# 判断文件类型
suffix = file_name.split('.')[-1]
if suffix == '264':
vdec_payload_type = K_PT_H264
elif suffix == '265':
vdec_payload_type = K_PT_H265
else:
print("未知的文件扩展名")
return
# 实例化视频解码器
vdec = vdecoder.Decoder(vdec_payload_type)
# 初始化显示设备
if display_type == Display.VIRT:
Display.init(display_type, width=vdec_width, height=vdec_height, fps=30)
else:
Display.init(display_type, to_ide=True)
# 初始化缓冲区
MediaManager.init()
# 创建视频解码器
vdec.create()
# 绑定显示
bind_info = vdec.bind_info(width=vdec_width, height=vdec_height, chn=vdec.get_vdec_channel())
Display.bind_layer(**bind_info, layer=Display.LAYER_VIDEO1)
vdec.start()
# 打开文件
with open(file_name, "rb") as fi:
while True:
os.exitpoint()
# 读取视频数据流
data = fi.read(STREAM_SIZE)
if not data:
break
# 解码数据流
vdec.decode(data)
# 停止视频解码器
vdec.stop()
# 销毁视频解码器
vdec.destroy()
time.sleep(1)
# 关闭显示
Display.deinit()
# 释放缓冲区
MediaManager.deinit()
print("vdec_test stop")
if __name__ == "__main__":
os.exitpoint(os.EXITPOINT_ENABLE)
vdec_test("/sdcard/examples/test.264", 800, 480) # 解码 H.264/H.265 视频文件