MaixPy Playback Video

Introduction

This document provides instructions for using the Play Video feature.

MaixPy supports playing h264, mp4 and flv video formats, note that currently only avc encoded mp4 and flv files are supported. Additionally, due to hardware encoder limitations, if you encounter issues decoding the video during playback, try re-encoding it with ffmpeg and then play it again. Refer to the following command:

ffmpeg -i input_video.mp4 -c:v libx264 -x264opts "bframes=0" -c:a aac -strict experimental output_video.mp4

Play MP4 video

An example of playing an mp4 video, the path to the video file is /root/output.mp4.

from maix import video, display, app, time

disp = display.Display()
d = video.Decoder('/root/output.mp4')
print(f'resolution: {d.width()}x{d.height()} bitrate: {d.bitrate()} fps: {d.fps()}')
d.seek(0)
while not app.need_exit():
    t = time.ticks_ms()

    ctx = d.decode_video()
    if not ctx:
        d.seek(0)
        continue

    img = ctx.image()
    disp.show(img)

    wait_ms = (ctx.duration_us() // 1000) - (time.ticks_ms() - t)
    wait_ms = wait_ms if wait_ms > 0 else 0
    time.sleep_ms(wait_ms)

Steps:

1. Import the module and initialise the camera

   from maix import video, display, app
   disp = display.Display()
   

   • disp = display.Display() is used to initialise the display to show the decoded image

2. Initialise the Decoder module

   d = video.Decoder('/root/output.mp4')
   

   • d = video.Decoder(‘/root/output.mp4’) is used to initialise the decoder and set the path to the video file that needs to be played. If you need to play flv files, you can fill in the path of the file with flv suffix, such as {your_file_path}.flv, if you need to play h264 files, you can fill in the path of the file with h264 suffix, such as {your_file_path}.h264

3. Set the decoding location

   d.seek(0)
   

   • can be used to set the position of the video to be played, in seconds.

4. Get the decoded image

   ctx = d.decode_video()
   img = ctx.image()
   

   • Each call returns a frame context, and you can obtain img through ctx.image(). Currently the decoded output only supports the NV21 format.

5. Display the decoded image

   disp.show(img)
   

   • When displaying images, you can use ctx.duration_us() to obtain the duration of each frame. It can be used to control the playback speed, and the unit is microseconds.

6. Done, see API documentation for more usage of Decoder.