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• Converting imges to video

  19 janvier 2014, par DanM

  I am using external camera with my application. The camera takes 9 pictures every second (9fps). The pictures are bitmaps 384x288. I need to create from this pictures a video file.

  What I have tried :

  • Using Jcodec

  The problem : jcodec is relatively slow, and for it to work properly i add the bitmaps to ArrayList and when the record stopped i convert the array to video. I takes to much time. For 30 sec video there is about 1 min rendering time.

  • Using native mediaCodec

  The problem : I could only generate AVI files (video/avc) that not readable in the original android player. I can not use what is written here : http://bigflake.com/mediacodec/ because I developing for API 16. I have tried using (video/mp4v-es) but the video is corrupted and not playable in any player.

  • Using FFmpeg

  The problem : Very complicated to implement in android, and I am not sure it will give me the result I needed after spending time to implement this. The result I need is to record video streaming as I get the bitmap without any delay.

  What can you suggest me ?

• ffmpeg : create a video from images and sounds

  27 septembre 2018, par Yuri Gusak

  You need to create a video from a set of pictures and sounds using ffmpeg.
  Set of pictures : frame_% d.jpg
  Sounds :
  sound1.mp3 (from 0 ms)
  sound2.mp3 (from 1000 ms)
  sound3.mp3 (from 2000 ms)
  

  I can create a video with one sound :

  -i frame_% d.jpg -i sound1.mp3 -r 30 -s 1280x720 -preset ultrafast -crf 25 -shortest movie.mp4

  and it works.

  But I need to add some sounds at different times. How can I do that ? May be -filter_complex will help ?

• How would I go about packaging an mp3 file into an mp4 container ?

  22 novembre 2020, par Jacob

  So here's the issue that I'm currently having. I need an audio player for iOS that will play mp3. Now at first glance this may seem like a trivial issue, just create an audio tag and give it the URL to the mp3 file. While this technically works, it's basically unusable since iOS needs to download the entire file before starting to play it. This results in a really long wait time when trying to play large mp3 files (could get close to a minute).
So the first thing I tried was to manually mimic the chunking that chrome does for playing mp3 files. I first sent a HEAD request to get the byte length of the audio file. Used that length / duration in seconds to get the average bytes per second and use that data to request chunks based on where the user seeks to. That didn't work since sometimes mp3 files contain metadata that throw off the calculation (like a cover image). Additionally, sometimes mp3 files use VBR (Variable Bit Rate) and then I'm well and truly screwed.

  



  So this lead me to thinking, Safari couldn't possibly require the end user to download an entire mp4 file before playing it. So I took an mp3 file, converted it to mp4 on an online converter and tested my theory out. Voila, it worked. Safari was streaming the mp4 file in chunks and the wait time went to close to 0. Alright, so now all I need to do is convert mp3 files to mp4 files. The problem now is, I have requirement not to use my server for converting these files. I want to offload this expensive operation to the client. After looking around for a bit I found a few wasm libraries to do this, great ! Nope. These wasm libraries are huge (24 MB) and would add an unacceptable amount to my already large bundles files. So this brings me to my question. Is there any way to "trick" safari into thinking that my mp3 file is mp4. What I've tried already :

  



  On input change event -> get the file -> clone it into a new Blob with a mimeType of video/mp4 and then upload that file to the server. Chrome plays this file no problem (probably because it detects it's an mp3 file), on Safari however it's unable to play the file.

  



  So my question is, is there any way to package the mp3 file in an mp4 container (Client Side !important) to "force" Safari into chunking the file.