Decoder Object

The Decoder object implements video data decoding functionality and includes several methods such as decode, set_img, get_img, and close. Detailed descriptions are provided below:

decode

【Function Description】

Enables the decode module and decodes the video file.

【Function Declaration】

Decoder.decode(file, video_chn, decode_type, width, height)

【Parameter Description】

Parameter Name	Description	Value Range
file	Filename of the file to be decoded	None
video_chn	Specifies the channel number of the video decoder	Range: 0–31
decode_type	Video decoding type	Range: 1–3, corresponding to H264, H265, and MJPEG respectively
width	Width of the input image to the decoding module	Up to 4096
height	Height of the input image to the decoding module	Up to 4096

【Usage】

#create decode object
decode = libsrcampy.Decoder()

#enable decode channel 0, resolution: 1080p, format: H264
ret = dec.decode("encode.h264", 0, 1, 1920, 1080)

【Return Value】

Returns a list containing two elements:

Return Value	Description
list[0]	0: Decoding succeeded; -1: Decoding failed
list[1]	Number of frames in the input bitstream file (valid only when decoding succeeds)

【Notes】

None

【Reference Code】

None

get_img

【Function Description】

Retrieves the output result from the decoding module.

【Function Declaration】

Decoder.get_img()

【Parameter Description】

None

【Usage】

ret = dec.decode("encode.h264", 0, 1, 1920, 1080)
print ("Decoder return:%d frame count: %d" %(ret[0], ret[1]))

img = dec.get_img()

【Return Value】

Return Value	Description
-1	Decoded data

【Notes】

This interface must be used after calling Decoder.decode() to create a decoding channel.

【Reference Code】

import sys, os, time

import numpy as np
import cv2
from hobot_vio import libsrcampy

def test_decode():
    #create decode object
    dec = libsrcampy.Decoder()

    #enable decode function
    #decode input: encode.h264, resolution: 1080p, format: h264
    ret = dec.decode("encode.h264", 0, 1, 1920, 1080)
    print ("Decoder return:%d frame count: %d" %(ret[0], ret[1]))
    
    #get decoder output
    img = dec.get_img()
    if img is not None:
        #save file
        fo = open("output.img", "wb")
        fo.write(img)
        fo.close()
        print("decode save img file success")
    else:
        print("decode save img file failed")

    dec.close()
    print("test_decode done!!!")

test_decode()

set_img

【Function Description】

Feeds a single encoded frame into the decoding module for decoding.

【Function Declaration】

Decoder.set_img(img, chn, eos)

【Parameter Description】

Parameter Name	Description	Value Range
img	Single-frame data to be decoded	None
chn	Decoder channel number	Range: 0–31
eos	Indicates whether decoding data has ended	0: Not ended; 1: Ended

【Usage】

None

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Notes】

This interface must be used after calling Decoder.decode() to create a decoding channel, and when creating the decoding channel, the file parameter must be left empty.

【Reference Code】

import sys, os, time

import numpy as np
import cv2
from hobot_vio import libsrcampy

def test_cam_bind_encode_decode_bind_display():
    #camera start
    cam = libsrcampy.Camera()
    # If you know the pipe_id and video_index, you can specify the first two arguments.
    # ret = cam.open_cam(0, 1, 30, [1920, 1280], [1080, 720])

    # If you do not know the pipe_id and video_index, you can use the following
    # code to detect them, and it will default to using the first detected camera.
    ret = cam.open_cam(0, -1, 30, [1920, 1280], [1080, 720])
    print("Camera open_cam return:%d" % ret)

    #enable encoder
    enc = libsrcampy.Encoder()
    ret = enc.encode(0, 1, 1920, 1080)
    print("Encoder encode return:%d" % ret)

    #enable decoder
    dec = libsrcampy.Decoder()
    ret = dec.decode("", 0, 1, 1920, 1080)
    print ("Decoder return:%d frame count: %d" %(ret[0], ret[1]))

    ret = libsrcampy.bind(cam, enc)
    print("libsrcampy bind return:%d" % ret)

    a = 0
    while a < 100:
        #get encode image from encoder
        img = enc.get_img()
        if img is not None:
            #send encode image to decoder
```dec.set_img(img)
            print("encode get image success count: %d" % a)
        else:
            print("encode get image failed count: %d" % a)
        a = a + 1

    ret = libsrcampy.unbind(cam, enc)
    dec.close()
    enc.close()
    cam.close_cam()
    print("test_cam_bind_encode_decode_bind_display done!!!")

test_cam_bind_encode_decode_bind_display()

close

【Function Description】

Close the decoder module.

【Function Declaration】

Decoder.close()

【Parameters】

None

【Usage】

None

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Notes】

The close interface must be called upon program exit to release resources.

【Example Code】

None