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• Trying to save frames as colored image using Ffmpeg in C++

  2 septembre 2021, par Tolga

  I am new to FFmpeg and I am trying to save the video frames as colored images. I have achieved saving them as grayscale using Netpbm, however, I need to save the frames as colored. I have tried implementing the code in this link.

  


  However, I get an error :

  


  'Exception thrown at 0x00E1FC4F (swscale-5.dll) in VideoDecoding2.exe:
 0xC0000005: Access violation writing location 0xCCCCCCCC.'


  


  Is there any way to improve this code or another way to save frames as colored ?

  


  Here is my code below.

  


  

  • src_pix_fmt is AV_PIX_FMT_YUV420p.

  


  • dst_pix_fmt is AV_PIX_FMT_RGB24.

  


  


  src_pix_fmt = avcc->pix_fmt;

src_width = avcc->width;
src_height = avcc->height;

dst_width = src_width;
dst_height = src_height;

numBytes = av_image_get_buffer_size(dst_pix_fmt, dst_width, dst_height, 0);

buffer = (uint8_t*)av_malloc(numBytes);

if ((ret = av_image_alloc(src_data, src_linesize, src_width, src_height, src_pix_fmt, 16)) < 0)
{
    printf("Couldn't allocate source image.\n");
    return 0;
}

av_image_fill_arrays(frameRGB->data, frameRGB->linesize, buffer, dst_pix_fmt, dst_width, dst_height, 0);

while (av_read_frame(avfc, packet) >= 0)
{
    ret = avcodec_send_packet(avcc, packet);
    if (ret < 0)
    {
        printf("Packets could not supplied to decoder.\n");
        return -1;
    }

    ret = avcodec_receive_frame(avcc, frame);
    printf("%d", ret);

    if (packet->stream_index == videoStream)
    {
        sws_ctx = sws_getContext(src_width, src_height, src_pix_fmt,
            dst_width, dst_height, dst_pix_fmt,
            SWS_BILINEAR, NULL, NULL, NULL);

        if (!sws_ctx)
        {
            printf("Cannot create scale context for conversion\n"
                "fmt:%s s:%dx%d --> fmt:%s s:%dx%d\n",
                av_get_pix_fmt_name(src_pix_fmt), src_width, src_height,
                av_get_pix_fmt_name(dst_pix_fmt), dst_width, dst_height);
            return 0;
        }

        sws_scale(sws_ctx, (const uint8_t* const*)frame->data, frame->linesize, 0, frame->height, dst_data, dst_linesize);

        FILE* f;
        char szFilename[32];
        int y;

        snprintf(szFilename, sizeof(szFilename), "frame%d.ppm", avcc->frame_number);
        fopen_s(&f, szFilename, "wb");
        
        if (f == NULL)
        {
            printf("Couldn't open file.\n");
            return 0;
        }
        
        fprintf(f, "P6\n%d %d\n255\n", dst_width, dst_height);

        for (y = 0; y < dst_height; y++)
            fwrite(frameRGB->data[0] + y * frameRGB->linesize[0], 1, dst_width * 3, f);
        
        fclose(f);
    }
}


  


• How do I save `RTSP` streams as `*.mp4` files in Golang ? [closed]

  14 septembre 2021, par Clancy Zeng

  I need to use Golang to save the data from the RTSP stream to a *.mp4 video file for a specified length of time.

  


  I wanted to install an FFmpeg application and then call a command like this from Golang to solve my needs.

  


  


  ffmpeg -i rtsp ://192.168.108.132:8554/profile0 -r 16 -tt 60 /tmp/test.mp4

  


  


  But installing FFMPEG takes up hundreds of megabytes of space.So this idea was rejected by the leadership.

  


  Is there a pure Golang implementation library that can address my needs ?Or is there a golang-only library that parses RTSP streams and saves them as *.MP4 video files ?

  


• I cant save the animation in ffmpeg

  22 mai 2021, par Gokul

  i tried various examples though i cant find proper solution. This is the example code of my project i want to save this in a mp4 format and i used ffmpeg. the animation was saved if I use df = pd.DataFrame(np.random.rand(250,3)) but it is not working for my sample code, it showed key error = 0. Note : df1 = pd.DataFrame(np.random.randint(5,15,[250,3])).
Any suggestion for this would be appreciated. Thank you in advance

  


  import pandas as pd
import numpy as np
import ma``tplotlib.pyplot as plt
import matplotlib.animation as animation

df = data.iloc[0:250, 4:12]
df1 = df2.iloc[:,0:3]

a1 = df.iloc[:,0]/2
a2 = df.iloc[:,1]/2
b1 = df.iloc[:,2]/2
b2 = df.iloc[:,3]/2
c1 = df.iloc[:,4]/2
c2 = df.iloc[:,5]/2
m1 = df1.iloc[:,0]
m2 = df1.iloc[:,1]
m3 = df1.iloc[:,2]

fig ,ax = plt.subplots()

l1, = ax.plot (vert1, vert2, 'ro', markersize = m1[0])
l2, = ax.plot (long1, long2, 'ro', markersize = m2[0])
l3, = ax.plot (tras1, tras2, 'ro', markersize = m3[0])

def init():    
    l1.set_data([],[])
    l2.set_data([],[])
    l3.set_data([],[])
    
    return (l1,l2,l3)

def animate(i,l1,l2,l3):
    
    l1.set_data(vert1[i], vert2[i])
    l1.set_markersize(m1[i])
    l2.set_data(long1[i], long2[i])
    l2.set_markersize(m2[i])
    l3.set_data(tras1[i], tras2[i])
    l3.set_markersize(m3[i])

    return (l1,l2,l3)

Writer = animation.writers['ffmpeg']
writer = Writer(fps= 100, metadata = dict(artist = 'me'), bitrate = 1800)

ani = animation.FuncAnimation(fig, animate, fargs=(l1,l2,l3), init_func=init, interval=10, blit=False)
ani.save('/Users/gokulthangavel/Downloads/basic_animation.mp4', writer = writer)

plt.show()