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• iPhone - A problem with decoding H264 using ffmpeg

  25 mars 2012, par HAPPY_TIGER

  I am working with ffmpeg to decode H264 stream from server.

  I referenced DecoderWrapper from http://github.com/dropcam/dropcam_for_iphone.

  I compiled it successfully, but I don't know how use it.

  Here are the function that has problem.

  - (id)initWithCodec:(enum VideoCodecType)codecType 
  
           colorSpace:(enum VideoColorSpace)colorSpace 
  
                width:(int)width 
  
               height:(int)height 
  
          privateData:(NSData*)privateData {
  
      if(self = [super init]) {
  
  
  
          codec = avcodec_find_decoder(CODEC_ID_H264);
  
          codecCtx = avcodec_alloc_context();
  
  
  
          // Note: for H.264 RTSP streams, the width and height are usually not specified (width and height are 0).  
  
          // These fields will become filled in once the first frame is decoded and the SPS is processed.
  
          codecCtx->width = width;
  
          codecCtx->height = height;
  
  
  
          codecCtx->extradata = av_malloc([privateData length]);
  
          codecCtx->extradata_size = [privateData length];
  
          [privateData getBytes:codecCtx->extradata length:codecCtx->extradata_size];
  
          codecCtx->pix_fmt = PIX_FMT_YUV420P;
  
  #ifdef SHOW_DEBUG_MV
  
          codecCtx->debug_mv = 0xFF;
  
  #endif
  
  
  
          srcFrame = avcodec_alloc_frame();
  
          dstFrame = avcodec_alloc_frame();
  
  
  
          int res = avcodec_open(codecCtx, codec);
  
          if (res < 0)
  
          {
  
              NSLog(@"Failed to initialize decoder");
  
          }
  
      }
  
  
  
      return self;    
  
  }

  What is the privateData parameter of this function ? I don't know how to set the parameter...

  Now avcodec_decode_video2 returns -1 ;

  The framedata is coming successfully.

  How solve this problem.

  Thanks a lot.

• Is there any way to control the video bitrate using FFmpeg Complex Filter other than -b:v ?

  8 février 2017, par srujith poondla

  I am trying to compress the video size by reducing the bitrate. I successfully achieved using -b:v in ffmpeg, its working perfectly. But that is not a filter so i am unable to chain the ffmpeg commands one after the other. Is there any other video filter in ffmpeg that controls the bitrate of the video so that i can chain the ffmpeg commands like mentioned in this link Filter Chaining FFmpeg

• How to fix the problem I'm having with FFmpeg ?

  23 février 2023, par John

  I'm working with the ffmpeg library to convert mp4 video files to mp3 audio files.
Here is my code :

  


  package com.exer;


import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Environment;
import android.widget.Toast;
import com.github.hiteshsondhi88.libffmpeg.ExecuteBinaryResponseHandler;
import com.github.hiteshsondhi88.libffmpeg.FFmpeg;
import com.github.hiteshsondhi88.libffmpeg.FFmpegLoadBinaryResponseHandler;

public class MainActivity extends Activity {
    
    FFmpeg ffmpeg;
    private ProgressDialog progressDialog;
    
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    
        
        
        try {
            setUp();
            String[] command = {
                "-i", getPaths()+"/dir/input.mp4", "-vn", getPaths()+"/dir/output.mp3"
            };
            //convert("ffmpeg -i input.mp4 -vn output.mp3");
            convert(command);
            
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), e.getCause().toString(), Toast.LENGTH_SHORT).show();
        }
    }
    
    
    public void setUp() throws Exception {
        
        if(ffmpeg == null) {
            
            ffmpeg = FFmpeg.getInstance(this);
            ffmpeg.loadBinary(new FFmpegLoadBinaryResponseHandler(){
                    
            @Override
            public void onFailure() {
                Toast.makeText(getApplicationContext(), "failed to load library", Toast.LENGTH_SHORT).show();   
            }
                    
            @Override
            public void onSuccess() {
                Toast.makeText(getApplicationContext(), "loaded!", Toast.LENGTH_SHORT).show();
            }
                    
            @Override
            public void onStart() {
                        
            }
                    
            @Override
            public void onFinish() {
                        
            }
                    
                    
            });
            
        }
        
    }
    
    
    private void convert(String[] cmd) throws Exception {
        
        ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler(){
            
            @Override
            public void onFailure(String message){
                super.onFailure(message);
            }
            
            @Override
            public void onFinish(){
                super.onFinish();
                Toast.makeText(getApplicationContext(), "finished!", Toast.LENGTH_SHORT).show();
            }
            
            @Override
            public void onStart(){
                super.onStart();
                Toast.makeText(getApplicationContext(), "start conversion...", Toast.LENGTH_SHORT).show();
            }
            
            @Override
            public void onProgress(String message){
                super.onProgress(message);
            }
        });
        
    
    }
    
    private String getPaths() {
        return Environment.getExternalStorageDirectory().getPath();
    }
    
}


  


  When I run the app, the Toast messages are shown :

  


  loaded!
start converting...
finished! as I write them in the functions, apart that nothing else happens the file is not converted what's wrong ?

  


  Here my manifest file :

  


  &lt;?xml version="1.0" encoding="utf-8"?>&#xA;<manifest package="com.exer">&#xA;    &#xA;    &#xA;    &#xA;    &#xA;    &#xA;        &#xA;            &#xA;                <action></action>&#xA;&#xA;                <category></category>&#xA;            &#xA;        &#xA;    &#xA;&#xA;</manifest>&#xA;

  


  I've tried to delete the specified file on the phone to see what erros I might got, but still those three Toasts.