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• ffmpeg : test if format is seekable

  20 mai 2021, par Diederick C. Niehorster

  How do i test if a format is seekable ?

  


  I have written code against the latest fmmpeg's (4.4) libavformat, libavcodec, etc. My code reads and decodes video files. Now i also want to support reading from avdevices, such as dshow (DirectShow) on Windows. That is possible through the same interface as i have already implemented, it just requires using the dshow format. Super nice ! But in my video file reader, i have some seek logic implemented, which is engaged in various instances. The problem is that the dshow format is not seekable (avformat_seek_file() returns -22, invalid argument). How do i detect that a format is not seekable ? I know that the AVFormatContext's pb member (AVIOContext) has a seekable field, but the dshow format leaves pb null (as it should be since the AVFMT_NOFILE flag is set for the format). How do i test if a format is seekable (so that if it is not, i can disable the seek logic) ? The implementation of avformat_seek_file() and the various functions it calls seems to have various callbacks, so i am not sure if simply this would do the trick : bool isSeekable = !!context->pb && context->pb->seekable!=0.

  


• Converting video to GIF in Android Studio

  21 novembre 2019, par Wolfiebae

  I am trying to make my app to accept videos from the phone’s library to be uploaded and converted into GIF format. My code is giving out this build error though :-

  error: <anonymous> is not abstract and does not override abstract method onReschedule(String,ErrorInfo) in UploadCallback
  
  </anonymous>

  and also this warning on my onActivityResult method :-

  Overriding method should call super.onActivityResult

  The code is as below : -

  public class Video2gif extends AppCompatActivity {
  
  
  
      private Button uploadBtn;
  
      private ProgressBar progressBar;
  
      private int SELECT_VIDEO = 2;
  
      private ImageView img1;
  
      private DownloadManager downloadManager;
  
      private Button download_btn;
  
      private String gifUrl;
  
  
  
      @Override
  
      protected void onCreate(Bundle savedInstanceState) {
  
          super.onCreate(savedInstanceState);
  
          setContentView(R.layout.activity_video2gif);
  
          MediaManager.init(this);
  
  
  
          progressBar = findViewById(R.id.progress_bar);
  
          MediaManager.init(this);
  
          img1 = findViewById(R.id.img1);
  
          uploadBtn = findViewById(R.id.uploadBtn);
  
  
  
          uploadBtn.setOnClickListener(new View.OnClickListener() {
  
              @Override
  
              public void onClick(View view) {
  
                  pickVideoFromGallery();
  
  
  
              }
  
              private void pickVideoFromGallery() {
  
                  Intent GalleryIntent = new Intent();
  
                  GalleryIntent.setType("video/*");
  
                  GalleryIntent.setAction(Intent.ACTION_GET_CONTENT);
  
                  startActivityForResult(Intent.createChooser(GalleryIntent,
  
                          "select video"), SELECT_VIDEO);
  
              }
  
          });
  
      }
  
      @Override
  
      protected void onActivityResult(int requestCode, int resultCode, final Intent data) {
  
  
  
          if (requestCode == SELECT_VIDEO && resultCode == RESULT_OK) {
  
              Uri selectedVideo = data.getData();
  
              MediaManager.get()
  
                      .upload(selectedVideo)
  
                      .unsigned("myid")
  
                      .option("resource_type", "video")
  
                      .callback(new UploadCallback(){
  
                          @Override
  
                          public void onStart(String requestId) {
  
                              progressBar.setVisibility(View.VISIBLE);
  
                              Toast.makeText(Video2gif.this,
  
                                      "Upload Started...", Toast.LENGTH_SHORT).show();
  
                          }
  
  
  
                          public void onProgress() {
  
                          }
  
  
  
                          public void onSuccess(String requestId, Map resultData) {
  
  
  
                              Toast.makeText(Video2gif.this, "Uploaded Succesfully",
  
                                      Toast.LENGTH_SHORT).show();
  
                              progressBar.setVisibility(View.GONE);
  
                              uploadBtn.setVisibility(View.INVISIBLE);
  
  
  
                              String publicId = resultData.get("public_id").toString();
  
  
  
                              gifUrl = MediaManager.get().url().resourceType("video")
  
                                      .transformation(new Transformation().videoSampling("25")
  
                                              .delay("200").height(200).effect("loop:10").crop("scale"))
  
                                      .resourceType("video").generate(publicId+".gif");
  
  
  
                              Glide.with(getApplicationContext()).asGif().load(gifUrl).into(img1);
  
                              download_btn.setVisibility(View.VISIBLE);
  
  
  
                          }
  
                          public void onError(String requestId, ErrorInfo error) {
  
                              Toast.makeText(Video2gif.this,
  
                                      "Upload Error", Toast.LENGTH_SHORT).show();
  
                              Log.v("ERROR!!", error.getDescription());
  
                          }
  
  
  
  
  
          });
  
      }
  
  }
  
  
  
  }

  I am also using Cloudinary to help process the video to GIF. Any help would be appreciated, many thanks !

• Lego Mindstorms RSO Format

  14 juillet 2010, par Multimedia Mike — General

  I recently read a magazine article about Lego Mindstorms. Naturally, the item that caught my eye was the mention of a bit of Lego software that converts various audio file formats to a custom format called RSO that can be downloaded into a Mindstorms project to make the creation output audio. To read different sources, one might be left with the impression that there is something super-duper top secret proprietary about the format. Such impressions do not hold up under casual analysis of a sample file.

  A Google search for "filetype:rso" yielded a few pre-made sample that I have mirrored into the samples archive. The format appears to be an 8-byte header followed by unsigned, 8-bit PCM. More on the wiki. If FFmpeg could gain an RSO file muxer, that would presumably be a heroic feat to the Lego hacking community.