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• How to kill command Exec in difference Function in Golang

  26 juillet 2022, par Tammam

  i'm making screen record web based using command exec to run FFMPEG. here I created a startRecording function but I am still confused about stopping the command process in the stopRecording function, because the command is executed in the startRecording function. How to stop a process that is already running in the srartRecording function in the stopRecording function ?

  


  here my code

  


  //Handler to create room/start record
func RoomCreate(c *fiber.Ctx) error {
    fileName := "out.mp4"
    fmt.Println(fileName)
    if len(os.Args) > 1 {
        fileName = os.Args[1]
    }

    

    errCh := make(chan error, 2)
    ctx, cancelFn := context.WithCancel(context.Background())
    // Call to function startRecording
    go func() { errCh <- startRecording(ctx, fileName) }()

    go func() {
        errCh <- nil
    }()
    err := <-errCh
    cancelFn()
    if err != nil && err != context.Canceled {
        log.Fatalf("Execution failed: %v", err)
    }
    
    return c.Redirect(fmt.Sprintf("/room/%s", guuid.New().String()))
}



//Function to run command FFMPEG
func startRecording(ctx context.Context, fileName string) error {
    ctx, cancelFn := context.WithCancel(ctx)
    defer cancelFn()
    // Build ffmpeg
    ffmpeg := exec.Command("ffmpeg",
        "-f", "gdigrab",
        "-framerate", "30",
        "-i", "desktop",
        "-f", "mp4",
        fileName,
    )
    // Stdin for sending data
    stdin, err := ffmpeg.StdinPipe()
    if err != nil {
        return err
    }
    //var buf bytes.Buffer
    defer stdin.Close()
    // Run it in the background
    errCh := make(chan error, 1)

    go func() {
        fmt.Printf("Executing: %v\n", strings.Join(ffmpeg.Args, " "))
        
        if err := ffmpeg.Run(); err != nil {
            return
        }
        //fmt.Printf("FFMPEG output:\n%v\n", string(out))
        errCh <- err
    }()
    // Just start sending a bunch of frames
    for {
        
        // Check if we're done, otherwise go again
        select {
        case <-ctx.Done():
            return ctx.Err()
        case err := <-errCh:
            return err
        default:
        }
    }
}

//Here function to stop Recording
func stopRecording(ctx context.Context) error {
//Code stop recording in here
} 


  


  Thanks for advance

  


• What's the difference between H265, x265, x264, H264 and which of these uses GPU instead of CPU and how to use H265 GPU NVIDIA acceleration in ffmpeg ?

  30 juillet 2022, par Fab98

  I'm not sure if
x264/5
use CPU and if h264/5 use GPU and also if h265 is basically HEVC_NVENC for NVIDIA GPU acceleration. So, if you could give me more info about these encoding types it would be great. I understood that, summing up a lot, x26* use CPU and are slower but more accurate while h26* are the opposite but h265 is the most recent and optimal trade off.
Furthermore, I was trying to convert a video using GPU acceleration and my question is :

  


  Does the following command tell to the GPU to use h265 to encode a video holding the same audio and at upgrading it at its maximum video quality ? Furthermore, are there other ways to express the same command ?

  


  ffmpeg.exe -hwaccel_output_format cuda -i "input" -c:v hevc_nvenc -preset medium -rc constqp -qp 0 -c:a copy "output"


  


• Not able to merge init.mp4 and seg-*.m4s with ffmpeg and python due to its file format difference

  1er février 2023, par XiBBaL

  I'm developing video downloader (only for free videos) for korean anime streaming site https://laftel.net/

  


  I guess laftel.net uses mpeg-dash for their streaming.
I found "init.mp4" file and "segments-number.m4s" files in chrome developer tools.

  


  Code below downloads seg-1.m4s (name of the first segment) to seg-239.m4s (name of the last segment) file and init.mp4 file and it works.

  


  
(Skip the beginning becasue there is a code that collects "Request-URL" for each .m4s files in network stream)


#variable "found" is part of the "Request-URL"

def curl_m4s():
    for i in range(1,240): #number of the .m4s segment file is constant at 239
        vid_url = f"https://mediacloud.laftel.net/{found}/video/avc1/2/seg-{i}.m4s"
        aud_url = f"https://mediacloud.laftel.net/{found}/audio/mp4a/eng/seg-{i}.m4s"
        
        if i < 10: #for single digit num
            os.system(f"curl {vid_url} > {location}/vids/vid00{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud00{i}.m4s")
            sleep(random.randint(1,3))
            
        elif i < 100: #for double digit num
            os.system(f"curl {vid_url} > {location}/vids/vid0{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud0{i}.m4s")
            sleep(random.randint(1,3))
            
        else: #for three digit num
            os.system(f"curl {vid_url} > {location}/vids/vid{i}.m4s")
            os.system(f"curl {aud_url} > {location}/auds/aud{i}.m4s")
            sleep(random.randint(1,3))

location = os.getcwd()

os.system(f"curl https://mediacloud.laftel.net/{found}/video/avc1/2/init.mp4 > {location}/vids/vid_init.mp4")
os.system(f"curl https://mediacloud.laftel.net/{found}/audio/mp4a/eng/init.mp4 > {location}/auds/aud_init.mp4")
os.system(f"curl https://mediacloud.laftel.net/{found}/stream.mpd > {location}/stream.mpd")

curl_m4s()
#use curl in cmd and downloads each of the .m4s (001 ~ 239)

    


  


  So in the vids folder i have "init.mp4" for video and "seg-1.m4s seg-239.m4s" for video
and in the auds folder i have "init.mp4" for audio and "seg-1.m4s seg-239.m4s" for audio

  


  Problem is, I cannot merge init file and segment files.
I have no idea about combining .mp4 and .m4s together.
There are a lot of example codes for merging init.m4s + seg-.m4s but I couldn't find init.mp4 + seg-.mp4 codes.

  


  I tried to merge segments together first, like this and it works.

  


  location = os.getcwd()

os.system(f"cd {location}")
os.system("copy /b vid*.m4s vid_full.m4s")


  


  and now, i want to merge init.mp4 becasue it has very much information about whole video files.
But how ??

  


  I tried these and none of them worked (looks like Successfull merge but it do not contain any watchable video)

  


  # vid_full is merged segment files (seg-1.m4s + ... + seg-239.m4s)
 
1. 
os.system("copy /b init.mp4 + vid*.m4s video_full.m4s")
os.system("ffmpeg -i video_full.m4s -c:a copy video_full.mp4")


2. 
os.system("type vid_init.mp4 index.txt > Filename.mp4")


3. 
import os 

os.system("ffmpeg -i vid_full.m4s -c:a copy vid_full.mp4")
os.system("copy /b vid_init.mp4 + vid_full.mp4 VIDEO.mp4")


  


  All problem occurs the format of the init file is .mp4. If it was .m4s I guess I could merge it.

  


  and I guess i must merge init file and segments files together both in .m4s format. Is it right ?
Via ffmpeg, i couldn't encode init.mp4 to init.m4s so this is the problme also.

  


  So, Please help me merge init.mp4 and segments.m4s

  


  All methods are wellcome at least it is based on python.

  


  

  1. I tried to merge init.mp4 + merged_segment.m4s but it failed

  


  2. I tried to convert init.mp4 to init.m4s via ffmpeg but it failed

  


  3. I tried to convert all the segments to .mp4 files and merge into init.mp4 but it failed

  


  


  I want to merge init file and segment files and make playable video.
Pleas Teach me how to do this.

  


  Links below are what I used for my test :

  


  [Laftel.net URL]
https://laftel.net/player/40269/46123

  


  [Request URL for init.mp4 (video)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/video/avc1/2/init.mp4

  


  [Request URL for init.mp4 (audio)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/audio/mp4a/eng/init.mp4

  


  [Request URL for seg-1.m4s (video)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/video/avc1/2/seg-1.m4s

  


  [Request URL for seg-1.m4s (audio)]
https://mediacloud.laftel.net/2021/04/46773/v15/video/dash/audio/mp4a/eng/seg-1.m4s