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• Need help finding a way to use avconv or ffmpeg to convert any video to an exact size and shape

  29 octobre 2013, par mikecole79

  This is for work. We have a system that supports streaming video, but we support multiple players. I have multiple systems that I COULD use for this. Currently, I've been using the media server that we use to stream the video, which has ffmpeg on it (running Red Hat 4). On that system, I've used :

   ffmpeg -i INPUT_FILE.mp4 -c:v libx264 -crf 23 -maxrate 3000k -bufsize 30000k -c:a aac -strict experimental -b:a 192k -filter:v "scale=iw*min($width/iw\,$height/ih):ih*min($width/iw\,$height/ih), pad=$width:$height:($width-iw*min($width/iw\,$height/ih))/2:($height-ih*min($width/iw\,$height/ih))/2" -f OUTPUT_FILE.mp4

  And I thought that it worked well. On one file I used to test, it seemed to display properly on both player types. On a different file, it did not appear properly. The input files are also in varying formats (mostly mp4, with a few m4g files) and different aspect ratios.

  We also have many desktop/laptop machines that are running Ubuntu 13.04 (comes with avconv) that I'd like to be able to use to format video as well. If I can get at least one of these systems to properly format video, that would be great, but ideally I'd like to figure out how to do this with both avconv AND ffmpeg so I can use any system.

  The problem that we're trying to solve is that one player is an Android DMP device, which will play a video of varying sizes properly by adding black bars at the sides or top/bottom as needed to keep the video sized properly. The other player is a Samsung Smart TV, which is SO Smart that it can reformat videos to fit the screen. Which sucks horribly, because if they're not sized to exactly the right format, it will stretch them one direction or another to make them be sized right. The resulting video show's people that appear to be 8 feet tall weighing 130 pounds, or 4 feet tall and 3 feet wide.

  Obviously, this isn't what we desire, but I lack the knowledge of avconv/ffmpeg to do anything to fix it. I need an expert, and I am not he. Nor is anyone I currently work with an expert on this subject. Anyone that is, I'd appreciate your help more than I can express via a web interface.

  Thanks !

• What video format will allow Android MediaPlayer.seekTo() to reliably provide frame-accurate scrubbing ?

  8 juillet 2015, par Tim Closs

  We have an iOS app that we are currently rebuilding for Android. The app relies on being able to scrub video with frame accuracy. We have 3D animations that are rendered out as single frames ; we build subsets of frames into lots of small (1-2 second) videos ; and the app provides the ability to scrub those videos and see each individual frame.

  The MP4 videos we initially created work fine on iOS. When we tried to get them working on Android (using the MediaPlayer class), we entered a world of pain ! What we need to do is find a video format that will play and allow frame-accurate scrubbing across all Android devices, using MediaPlayer.seekTo(). Initially we are targetting Android 3.0 and above, but we probably want to stretch back to 2.3.3 after our initial release. Here’s what I’ve discovered so far :

  (A) Android claims that H264 "baseline profile" should be supported everywhere : (URL). However, within that, there are dozens of other settings that may or may not be supported. Is there a more fine-grained list anywhere ? Currently we are converting to H264 within an MP4 container.

  (B) I haven’t yet seen an Android device that will accurately scrub H264 files without inserting keyframes ("intra frames"). iOS will happily take H264 files without keyframes and provide accurate scrubbing. It seems that, to allow accurate scrubbing, we need to insert a keyframe for every frame of the video (the relevant ffmpeg setting is "-g 1"). This significantly increases the file size.

  (C) However, inserting a keyframe for every frame results in a video that will not play at all on the Samsung Galaxy Note 3 (Snapdragon chipset I believe). Reducing the keyframes to every second frame or above seems to work (ffmpeg setting "-g 2").

  To summarise :
  MediaPlayer.seekTo() seems very dependent on the video format, and varies across devices. Is this the intention ? Is there a base level of behaviour that seekTo() is supposed to provide, regardless of format ?

  What video format that will allow frame-accurate scrubbing (using MediaPlayer.seekTo()) across all Android devices (at least for 3.0 and above ?)

• Connecting to RTSP stream via FFMpeg - 'could not find codec parameters for stream 0'

  14 novembre 2013, par user2992545

  I'm a beginner in the FFMpeg world, so please excuse me my overall level of knowledge and any mistakes.

  What I have here is a DVR, made by ITX Security. I have an SDK for it and currently I'm trying to connect to its RTSP using FFMPEG. I've been partially succesfull (i think), the best what I got was :

  `(...)bin>ffplay -user-agent "ITX Security" rtsp://ADMIN:1234@192.168.2.130:5554/live/
  
  
  
  [rtsp @ 02a242e0] UDP timeout, retrying with TCPB sq=0B f=0/0
  
  [rtsp @ 02a242e0] method PAUSE failed: 501 Not Implemented
  
  [rtsp @ 02a242e0] Could not find codec parameters for stream 0 (Video: h264):unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  rtsp://ADMIN:1234@192.168.2.130:5554/live/: could not find codec parameters
  
  
  
  nan:  0.000 fd=0 aq=    0KB vq=    0KB sq=    0B f=0/0`

  Is it really indicating that it has trouble in playing the stream (because it lacks a proper codec ?) - or am I just not getting the point ?

  I've captured traffic between my computer and the DVR in question, and something is happening (at least that's what Wireshark says).

  https://www.dropbox.com/s/j65lige244kg8jt/rtsp_ffmpeg.pcap

  What am I doing wrong ?

  Regards.