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• Python : mp3 to wave.open(f,'r') through ffmpeg pipe

  7 avril 2015, par user2754098

  I’m trying to decode mp3 to wav using ffmpeg :

  import alsaaudio
  
  import wave
  
  from subprocess import Popen, PIPE
  
  
  
  with open('filename.mp3', 'rb') as infile:
  
      p=Popen(['ffmpeg', '-i', '-', '-f', 'wav', '-'], stdin=infile, stdout=PIPE)
  
      ...

  Next i want redirect data from p.stdout.read() to wave.open(file, r) to use readframes(n) and other methods. But i cannot because ’file’ in wave.open(file,’r’) can be only name of file or an open file pointer.

      ...
  
      file = wave.open(p.stdout.read(),'r')
  
      card='default'
  
      device=alsaaudio.PCM(card=card)
  
      device.setchannels(file.getnchannels())
  
      device.setrate(file.getframerate())
  
      device.setformat(alsaaudio.PCM_FORMAT_S16_LE)
  
      device.setsetperiodsize(320)
  
      data = file.readframes(320)
  
      while data:
  
          device.write(data)
  
          data = file.readframes(320)

  I got :

  TypeError: file() argument 1 must be encoded string without NULL bytes, not str

  So is it possible to handle data from p.stdout.read() by wave.open() ?
  Making temporary .wav file isn’t solution.

  Sorry for my english.
  Thanks.

• How to overlay images sequence from pipe over a video stream with ffmpeg ?

  7 juin 2018, par Dotan Simha

  I’m trying to figure out an issue with ffmpeg.
  I have the following installation :
   DeckLink Mini Recorder Card (for HDMI input)
   DeckLink Mini Monitor Card (for HDMI output)

  I’ve successfully managed to take the HDMI input from the Decklink card and output is as-is to the output card with the following command :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I tried to add a complex-filter to add an overlay of an image, with the following command, and it works :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i ./tools/bin/windows/2.png -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I’m getting a realtime feed from the decklink recorder, the image is added to the stream, and it outputs it to the output HDMI card. Everything seems to work.

  Now I tried to change the static image path to use stdin (pipe:0), and I have a tool that constantly streaming PNG images to stdout :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i pipe:0 -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  The result that i’m getting on the output HDMI card is a static image, of the first frame.
  The output of ffmpeg also changes now, and it looks like it stuck of the first-second of the stream :

  ```
  frame= 30 fps=7.4 q=-0.0 size=N/A time=00:00:01.00 bitrate=N/A speed=0.247x

  frames : 30,
  currentFps : 7,
  currentKbps : NaN,
  targetSize : NaN,
  timemark : ’00:00:01.00’
  ```

  It just remains on 00:00:01.00 and never changes.

  I tried to find the issue, and did the following :

  • Tried to stream Decklink Recorder -> static png file overlay -> Decklink Monitor = IS WORKS

  • Tried to stream static png file -> Decklink Monitor = IS WORKS

  • Tried to stream pipe:0 (PNG files) -> Decklink Monitor = IS WORKS

  • Tried to stream Decklink Recorder -> pipe:0 (PNG files overlay) -> RAW AVI file IS WORKS

  The only issue is with :
   Tried to stream Decklink Recorder -> pipe:0 (PNG files) overlay -> Decklink Monitor DOES NOT WORK

  I suspect that Decklink output is more strict, and my pipe:0 with the PNG images is not stable, and the combination of both causes it to freeze.

  Any idea how to solve it ? :(

  Thanks !

• Why is ffmpeg choking on this particular PNG file ?

  13 novembre 2022, par kohloth

  I'm trying to make a video out of 4 still images with ffmpeg.

  


  This is the command I am having trouble with getting working at the moment :

  


  ffmpeg -y -loop 1 -framerate 24 -t 3 \
-i ./images/title-card.png -loop 1 -framerate 24 -t 4 \
-i ./images/001.png -loop 1 -framerate 24 -t 4 \
-i ./images/002.png -loop 1 -framerate 24 -t 3 \
-i ./images/003.png -loop 1 -framerate 24 -t 4 \
-filter_complex "[0][1][2][3]concat=n=4:v=1:a=0" \
/tmp/silentVideoTest.mp4


  


  Unfortunately, I get this error :

  


  [Parsed_concat_0 @ 0x5603df1c4080] Input link in1:v0 parameters (size 1024x1024, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1024x1024, SAR 3937:3937)
[Parsed_concat_0 @ 0x5603df1c4080] Failed to configure output pad on Parsed_concat_0
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #3:0


  


  I have no idea what this error means. But if I use a different png for the first image, it works fine. I understand that there is something about the first png that ffmpeg does not like ; the SAR, which I believe is some kind of png metadata bit or something ?

  


  Problem is :

  


  

  • The error is confusing to me

  


  • I see no option to set the SAR when exporting images from Krita, Pinta, or Photopea.

  


  • I do not know how to view the SAR value of an image, so I can't verify that this is really the problem

  


  


  Also, whats more is, I've used this command in the past to change an image's SAR (I think) but it seems to only work half the time ?

  


  ffmpeg -i title-card.png -vf setsar=1 title-card-new-sar.png


  


  No idea what the value of setsar should be, so I am using 1.

  


  Would love if someone could tell me how to get it to work. In particular, how do I view the SAR of a PNG file ?

  


  Maybe I am naieve, but shouldn't ffmpeg just be able to accept png images that are the same dimensions, compression, and stitch em together without errors ? i.e. Is there an option just to say "Fix the SAR ?" or "Use the SAR of the first image for all images ?"

  


  ---

  


  Edit : Trying it on some different images, having set the SAR with ffmpeg -i ./card.png -vf setsar=1 ./card-new-sar.png, I get a similar error :

  


  [Parsed_concat_0 @ 0x55e7b6b8b640] Input link in2:v0 parameters (size 1024x1024, SAR 2834:2834) do not match the corresponding output link in0:v0 parameters (1024x1024, SAR 1:1)
[Parsed_concat_0 @ 0x55e7b6b8b640] Failed to configure output pad on Parsed_concat_0
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #26:0


  


  ffmpeg still seems to complain that the SARs don't match...but surely, as its a ratio, a SAR of 2834:2834 does match a SAR of 1:1 ?

  


  ---

  


  Edit : Tried setting the SAR with ffmpeg -i ./card.png -vf setsar=2834:2834 ./card-new-sar.png, but now the error is (size 1024x1024, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1024x1024, SAR 2834:2834).