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• Saving a continuous stream of images from ffmpeg image2pipe

  11 février 2020, par Mina

  I am trying to save a sequence/continuous images from ffmpeg image2pipe in go. The problem with the code below that it does only save the first image in the stream due to the blocking nature of io.Copy since it waits for the reader or the writer to close.

  package main
  
  
  
  import (
  
      "fmt"
  
      "io"
  
      "log"
  
      "os"
  
      "os/exec"
  
      "strconv"
  
      "time"
  
  )
  
  
  
  //Trying to get png from stdout pipe
  
  
  
  func main() {
  
      fmt.Println("Running the camera stream")
  
      ffmpegCmd := exec.Command("ffmpeg", "-loglevel", "quiet", "-y", "-rtsp_transport", "tcp", "-i", "rtsp://admin:123456@192.168.1.41:554/h264Preview_01_main", "-r", "1", "-f", "image2pipe", "pipe:1")
  
  
  
      ffmpegOut, err := ffmpegCmd.StdoutPipe()
  
      if err != nil {
  
          return
  
      }
  
  
  
      err = ffmpegCmd.Start()
  
  
  
      if err != nil {
  
          log.Fatal(err)
  
      }
  
  
  
      count := 0
  
      for {
  
          count++
  
          t := time.Now()
  
          fmt.Println("writing image" + strconv.Itoa(count))
  
          filepath := "image-" + strconv.Itoa(count) + "-" + t.Format("20060102150405.png")
  
  
  
          out, err := os.Create(filepath)
  
          if err != nil {
  
              log.Fatal(err)
  
          }
  
          defer out.Close()
  
  
  
          _, err = io.Copy(out, ffmpegOut)
  
          if err != nil {
  
              log.Fatalf("unable to copy to file: %s", err.Error())
  
          }
  
      }
  
      if err := ffmpegCmd.Wait(); err != nil {
  
          log.Fatal("Error while waiting:", err)
  
      }
  
  }

  I implemented my own save and copy function based on the io.Copy code https://golang.org/src/io/io.go

  func copyAndSave(w io.Writer, r io.Reader) error {
  
      buf := make([]byte, 1024, 1024)
  
      for {
  
          n, err := r.Read(buf[:])
  
          if n == 0 {
  
  
  
          }
  
          if n > 0 {
  
              d := buf[:n]
  
              _, err := w.Write(d)
  
              if err != nil {
  
                  return err
  
              }
  
          }
  
          if err != nil {
  
              return err
  
          }
  
  
  
      }
  
      return nil
  
  }

  then I updated the for loop in my main function to the below block but still I am only getting the first image in the sequence. due to r.Read(buf[:]) is being a blocking call.

  for {
  
          count++
  
          t := time.Now()
  
          fmt.Println("writing image" + strconv.Itoa(count))
  
          filepath := "image-" + strconv.Itoa(count) + "-" + t.Format("20060102150405.png")
  
  
  
          out, err := os.Create(filepath)
  
          if err != nil {
  
              log.Fatal(err)
  
          }
  
          defer out.Close()
  
  
  
          err = copyAndSave(out, ffmpegOut)
  
          if err != nil {
  
              if err == io.EOF {
  
                  break
  
              }
  
              log.Fatalf("unable to copy to file: %s", err.Error())
  
              break
  
          }
  
      }

• Physical Calculus Education

  2 septembre 2011, par Multimedia Mike — General

  I have never claimed to be especially proficient at math. I did take Advanced Placement calculus in my senior year of high school. While digging through some boxes, I found an old grade report from that high school year. I wondered what motivated me to save it. Maybe it’s because it offered this clue as to why I can’t perform adequately in math class :

  
  
  

  Mystery solved : I did not wear proper P.E. attire to calculus class.

• How to set metadata year for a mp3 file and fetch it back in android ?

  6 mai 2019, par Aashit Shah

  I have been changing the metadata of input mp3 file and storing it in output all the metadata is successfully changing but the year metadata is getting as null.

  Below is my code.

  This is how I fetch the metadata in android :

       MediaMetadataRetriever mmr = new MediaMetadataRetriever();
  
                mmr.setDataSource(input);
  
                String Album = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ALBUM);
  
                String Artist = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ARTIST);
  
                String Title = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_TITLE);
  
                String Composer = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_COMPOSER);
  
                String Genre = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_GENRE);
  
                String Year = mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_YEAR);
  
                Log.e("date","date"+mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DATE));