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• Recording MP3 file from iphone using FFMPEG

  16 octobre 2014, par harit shah

  I am trying to record an mp3 file from iphone. It seems it is not possible so next option I am trying is recording it with aac encoding and convert it with ffmpeg exe to mp3.

  I am recording the m4a file with following code :

  // Set the audio file
  
  NSArray *pathComponents = [NSArray arrayWithObjects:
  
                             [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject],
  
                             @"MyAudioMemo.aac",
  
                             nil];
  
  NSURL *outputFileURL = [NSURL fileURLWithPathComponents:pathComponents];
  
  
  
  // Setup audio session
  
  AVAudioSession *session = [AVAudioSession sharedInstance];
  
  [session setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];
  
  UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
  
  AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);
  
  
  
  NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] initWithCapacity:10];
  
  NSNumber *formatObject;
  
  formatObject = [NSNumber numberWithInt: kAudioFormatMPEG4AAC];
  
  
  
  [recordSettings setObject:formatObject forKey: AVFormatIDKey];
  
  [recordSettings setObject:[NSNumber numberWithFloat:44100.0] forKey: AVSampleRateKey];
  
  [recordSettings setObject:[NSNumber numberWithInt:1] forKey:AVNumberOfChannelsKey];
  
  // [recordSettings setObject:[NSNumber numberWithInt:12800] forKey:AVEncoderBitRateKey];
  
  // [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
  
  [recordSettings setObject:[NSNumber numberWithInt: AVAudioQualityHigh] forKey: AVEncoderAudioQualityKey];

  so when I try to convert it using ffmpeg -i 1.m4a 1.mp3 it says invalid input found while reading 1.m4a. I tried different encoding but everytime I get the same error. Any help on this would be life saving.

  Thanks.

• Is there anyway to tell if an openCV cap.read() call will fail before it begins to parse a video ?

  18 novembre 2022, par aris-t

  Problem : I am per frame parsing very long videos with a complex algorithm for AI applications in python. This is a slow and long process even using multiprocessing and threading tricks. Therefore it is very annoying when it dies half way through its process due to an open CV issue with the video.

  


  Request : Does anyone know a good way in python for open cv to raise an error before it begins to parse a video if the video would later throw a fatal error or None from cap.read() ? An added bonus would for the solution to at least give me a frame number and a reason so that I may edit or reconvert the video to fix this.

  


  Latest Issue :

  


  [h264 @ 0x41cad80] Invalid NAL unit size (-66445153 > 10189).
[h264 @ 0x41cad80] Error splitting the input into NAL units.


  


  Thanks in advance.

  


• ffmpeg create thumbnail image of multiple images from video

  21 janvier 2018, par Michael Yousef

  So I want to create a thumbnail image that consists of multiple images from a single video. I’m looking to make them 4x8, and I want to spread out the images uniformly throughout the video.

  Ideally the final product should show 32 image captures, all downscaled to a reasonable size so they can fit on screen at the same time. Also, I’d like to have the final product have some overhead text like the video title, and I’d like to put the timestamp in the images as well.

  

  This is an example of what I want to do. The text at the top and the timestamp in the images. This one’s 6x4 and I want 4x8 but other than that it looks about what I want.

  I think ffmpeg probably has something to do this but I can’t seem to figure it out. I can generate individual screens but not collapse them into one. It’s also slower than programs I’ve used to do this in the past, not sure how they can do it as fast as they do. If I can’t get ffmpeg to do this, I’m open to using Python to accomplish this.