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• avcodec_decode_audio4 decoded data different on device and simulator

  5 décembre 2013, par Jona

  I'm having issues where the decoded audio sounds punchy/garbled simply can't tell what is being heard when decoded on an iPhone/iPad device. However, when decoding the audio on simulator the audio is perfect.

  I do realize emulator runs on a different CPU architecture i386 while actual device is ARMv7 so the issue could be something around that.

  I have printed the compressed data on device and simulator before being decoded and it matches. Then I printed the decoded data for device and simulator and they are different. That leads me to think something is happening with the decoder. I can see that it is not a byte swap issue since the data is just completely different.

  Any ideas on what I could or look into ? I don't have this issue on Android...

  First decoded audio frame.

  DEVICE :

  0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x08, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0xda, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  EMULATOR :

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  ---

  UPDATE 1
  I was able to resolve the issue by disabling asm with --disable-asm. Something must not be working correctly with the ARM asm files.

• AWS Easiest way to generate video thumbnails without transcoding/MediaConvert

  6 février 2021, par dfranca

  I used to have a pipeline for transcoding video and generate the thumbnail running on MediaConvert.
Due to the high costs and because most of my videos are already on H264 I came to the conclusion that MediaConvert is not necessary
But I still want to have the thumbnail of course, to show on the videos list

  


  I have tried a few approaches :

  


  

  • Just removed the video output from the MediaConvert -> doesn't work, MediaConvert requires at least one video output, which is annoying, but ok

  


  • Changed my lambda to not create the pipeline and create the thumbnail using ffmpeg -> Works nice for small videos, but I can have videos up to 2GB, and for that I end up on lambda limitations of tmp storage and time (as I have to download the file from S3)

  


  


  Another approaches I thought about :

  


  

  • Using EFS attached to the lambda, but it seems that it is a bit expensive, and not sure if it works as I expect

  


  • Moving to a EC2 instance instead of lambda and a SQS to communicate with the instance, but this adds a lot of complexity and moving parts to something that I want to be simple and that has only one function : generate ONE thumbnail, it seems I'm overcomplicating

  


  • Using a client-side solution and capturing the thumbnail on the fly while loading the list of video, not sure if this will work and how performance would be affected.

  


  


  It would be perfect if AWS provides a similar service as MediaConvert, but that I could have thumbnails only output, but I couldn't find anything, not even close.

  


  Do you have any other idea on how could I approach this in the simplest way possible ?

  


• Can anyone help merge these 2 FFmpeg commands ?

  7 juin 2019, par WebDev

  i have two commands which are part of a larger set of commands. basically i need to merge these two into one command to speed things up. can anyone help me please ?

  ffmpeg -y -f concat -safe 0 -protocol_whitelist "file,http,https,tcp,tls" -i "photos.txt" -i "mainscreen.png" -i "audio.mp3" -filter_complex "scale=3840x2160,zoompan=z='if(lte(zoom,1.0),1.2,max(1.001,zoom-0.0015))':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=1280x720:fps=15:d=120, overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2, drawtext=fontfile=font.otf:text='%%~ni':fontcolor=black:fontsize=32:x=90:y=582" -preset veryfast -tune stillimage -shortest -pix_fmt yuv420p "slideshow.mp4"
  
  
  
  ffmpeg -y -i "slideshow.mp4" -filter_complex "[0:a]showwaves=mode=cline:s=110x36:r=15:scale=sqrt:colors=0x222222,colorkey=0x000000:0.01:0.1,format=yuva420p[v];[0:v][v]overlay=77:444,scale=1280:720[outv]" -map "[outv]" -map 0:a -preset veryfast "done.mp4"

  firstly creates a slideshow and adds text.
  then draws a showwaves effect onto the video.

  thank you in advance

  UPDATE :

  from Gyan’s response, and after tinkering for a while, it kind of works how i needed it to. it does what I wanted, but keeps throwing "depreciated pixel format" error. heres the updated command once i finished. can you spot the problem ? and is the command written properly ?

  ffmpeg -y -f concat -safe 0 -protocol_whitelist "file,http,https,tcp,tls" -i "images.txt" -i "screen.png" -i "audio.mp3" -filter_complex "scale=3840x2160,zoompan=z='if(lte(zoom,1.0),1.2,max(1.001,zoom-0.0015))':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=1280x720:fps=15:d=120, overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2, drawtext=fontfile=Assets/Fonts/font.otf:text='%%~ni':fontcolor=black:fontsize=32:x=90:y=582[v];[2:a]showwaves=mode=cline:s=110x36:r=15:scale=sqrt:colors=0x222222,colorkey=0x000000:0.01:0.1,format=yuva420p[w];[v][w]overlay=77:444,scale=1280:720[outv]" -map "[outv]" -map 2:a -c:v libx264 -c:a aac -preset veryfast -shortest -pix_fmt yuv420p "done.mp4"

  SECOND UPDATE :

  thanks to Gyan (once again) for helping me better understand the command. here is the final code which does what I need :

  ffmpeg -y -f concat -safe 0 -protocol_whitelist "file,http,https,tcp,tls" -i "images.txt" -i "screen.png" -i "tmp.audio.mp3" -filter_complex "[0]scale=3840x2160,zoompan=z='if(lte(zoom,1.0),1.2,max(1.001,zoom-0.0015))':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=1280x720:fps=15:d=120, overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2, drawtext=fontfile=font.otf:text='%%~ni':fontcolor=black:fontsize=32:x=90:y=582[v];[2:a]showwaves=mode=cline:s=110x36:r=15:scale=sqrt:colors=0x222222,colorkey=0x000000:0.01:0.1,format=yuva420p[w];[v][w]overlay=77:444,scale=1280:720[outv]" -map "[outv]" -map 2:a -preset veryfast -shortest -pix_fmt yuv420p "done.mp4"

  only change from Gyan’s code is i removed [p] ;[1][p] and replaced with a comma to achieve what I needed. seems to work perfect now, ignoring the depreciated pixels warning.

  FINAL UPDATE :
  Gyan’s updated code works perfect, a massive thank you to you sir. you also helped me understand your work which was very helpful.