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• Simultaneous Recording and Real-Time Display Using ffmpeg with DeckLink

  9 décembre 2023, par ark1974

  I am currently working with a DeckLink Duo card, specifically utilizing port 2. My objective is to use FFmpeg to ingest RAW HD SDI, save it as an MP4 file, and concurrently display the incoming SDI video on the computer screen in real-time.

  


  I have experimented with various FFmpeg command lines, combining decklink and sdl options, to achieve this dual functionality :

  


  ffmpeg -f decklink -i 'DeckLink Duo@2' -c:v libx264 -preset ultrafast -tune zerolatency -f sdl "My Screen"


  


  However, I am encountering challenges in achieving both recording and real-time display simultaneously.

  


  I would appreciate any insights, suggestions, or alternative approaches to enable the concurrent recording and display of SDI video using DeckLink with ffmpeg.

  


• IPython.display Video giving an unplayable "empty" video when trying to run an animation from previous plots (Using ffmpeg)

  17 novembre 2023, par drhode

  I am working on a crater simulation project for a class and am running into a problem when it comes to creating a video. The general project is for us to simulate a surface being hit by craters until it becomes saturated. The code works, however, if I print out every graph in the simulation it would be thousands of graphs until sat is reached and then I would have to manually clip them all together. To circumvent this, I would like to take all the graphs and put them into an animation. I however, have no idea where to even start.

  


  for reference, here is main code block :

  


  import matplotlib.pyplot as plt
import numpy as np
import math
import os
import matplotlib.animation as ani

#I have removed the definitions and class implementation for sake of simplicity and space

ani.writers.list()
FFMpegWriter = ani.writers['ffmpeg']
writer = FFMpegWriter(fps = 10)
fig = plt.gcf()
figure = plt.figure()
fig.patch.set_alpha(1.0)

with writer.saving(figure, "sine.mp4", 150):
    while sat_counter !=1:#while loop that will introduce new crater each iteration

        new_crater = generate_crater()
        new_crater.age = sat_counter
        random_crater_list.append(new_crater)

        i =0

        while i < len(random_crater_list):#looping through the crater list and comparing new crater to all others


            old_crater = random_crater_list[i]


            overlap = square_overlap(old_crater, new_crater)#checks if old crater should be covered/removed by new crater
          

            if overlap == True:
                    random_crater_list.remove(old_crater)
                    i=i-1

                    
            else:
                pass

            i=i+1

        sat = Saturation(random_crater_list)# checks the saturation of the graph and returns a a number between 0 and 100
        if sat > 90:
            sat_counter = 1#base condition used to break the while loop

        writer.grab_frame()
plot_craters(random_crater_list)                   



  


  Here is what the final graph looks like
saturated surface

  


  I have tried to use the IPython.display video :

  


  
Video("sine.mp4", embed = True, width = 320, height = 320)


  


  This however loads an empty video that is unplayable.
empty video

  


• ffplay - How to display “pts_time=…” while playing the video ?

  14 novembre 2023, par Deni

  I am a beginner in ffmpeg and need to know how to use ffplay in Linux to display the pts_time while the video is playing.

  


  I'm interested in seeing the pts_time of each frame. So I can check if the adblock begins with an IDR frame.

  


  In windows machine I use the following commands to identify if the adbock begins with an IDR frames (by using pts-time infos) :

  


   ffplay -vf "drawtext=fontfile=/Tools/ffmpeg/arial.ttf:text='%{pts}%{pict_type}':fontsize=(h/10):box=1:x=(w-tw)/2:y=h-(2*lh)" c:/video.ts
 
    ffprobe -show_frames -show_entries frame=pts_time,pict_type,key_frame -select_streams v c:/video.ts | grep -E --after-context=5 --before-context=5 "49635.045689"


  


  I need the PTS time to be displayed as in the attached photo :

  


  

  


  In Linux I am able to play the video with the command ffplay video.ts and with the help of VcXsrv Windows X Server to be able to access the graphical interface of the Linux server from my Windows PC.

  


  and with the following ffprobe comand, I am able to see the frames details and the pts_time of each frame :

  


  ffprobe -select_streams v -show_frames video.ts
*[FRAME]
media_type=video
stream_index=5
**key_frame=1** */* it is a IDR frame*
pkt_pts=4467154112
**pkt_pts_time=49635.045689** 
pkt_dts=4467155912
pkt_dts_time=49635.065689
best_effort_timestamp=4467154112
best_effort_timestamp_time=49635.045689
pkt_duration=1800
pkt_duration_time=0.020000
pkt_pos=2262204
pkt_size=46939
width=1280
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=3:2
pict_type=I
coded_picture_number=21
display_picture_number=0
interlaced_frame=1
top_field_first=1
repeat_pict=0
color_range=tv
color_space=bt709
color_primaries=bt709
color_transfer=bt709
chroma_location=left
[SIDE_DATA]


  


  Any help would mean a lot to me !