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• Using ffmpeg with libfdk-aac, encoding HE-AAC v1 and mono actually, but in decoding ffmpeg show HE-AAC v2 and stereo [closed]

  13 novembre 2024, par olojzyg

  ffmpeg encode command :

  


  


  ffmpeg -i aac_128000_f32le_22050_1.wav -c:a libfdk_aac -profile:a
aac_he -b:a 64k -channels 1 test.aac

  


  


  output :

  


  [aist#0:0/pcm_s16le @ 000001d38ecfe340] Guessed Channel Layout: mono
  Input #0, wav, from 'aac_128000_f32le_22050_1.wav':   Duration: 00:00:06.48, bitrate: 359 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, mono, s16, 352 kb/s
  Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (libfdk_aac)) 
  Press [q] to stop, [?] for help Output #0, adts, to 'test.aac':
  Metadata:
        encoder         : Lavf61.7.100   
        Stream #0:0: Audio: aac (HE-AAC), 22050 Hz, mono, s16, 64 kb/s
          Metadata:
            encoder         : Lavc61.19.100 libfdk_aac 
[out#0/adts @ 000001d38ecf8680] video:0KiB audio:53KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.000000%
 size=      53KiB time=00:00:06.47 bitrate=  67.0kbits/s speed= 296x


  


  but decode this test.aac, I think HE-AAC and mono is corrent, but it show HE-AAC v2 and stereo, why ?
decode command :

  


  


  ffmpeg -i test.aac -f null -

  


  


  decode output :

  


  [aac @ 0000020ffcab3d40] Estimating duration from bitrate, this may be inaccurate
 Input #0, aac, from 'test.aac':   Duration: 00:00:06.78, bitrate: 63 kb/s
 Stream #0:0: Audio: aac (HE-AACv2), 22050 Hz, stereo, fltp, 63 kb/s
 Stream mapping:
 Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))
 Press [q] to stop, [?] for help Output
#0, null, to 'pipe:':
   Metadata:
    encoder         : Lavf61.7.100
   Stream #0:0: Audio: pcm_s16le, 22050 Hz, stereo, s16, 705 kb/s
      Metadata:
        encoder         : Lavc61.19.100 pcm_s16le
[out#0/null @ 0000020ffcac8bc0] video:0KiB audio:584KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
size=N/A time=00:00:06.78 bitrate=N/A speed=1.6e+03x


  


  what happened ? test.aac is also displayed as 2 channels in Audition. But 1 channel is displayed in MediaInfo, and ADTS header is corrent :

  


  


  channel_configuration : 1 (0x1) - (3 bits)

  


  


• Using FFMPEG command to read the frame and show using the inshow function in opencv

  28 novembre 2024, par HARSH BHATNAGAR

  I am trying to get the frame using the ffmpeg command and show using the opencv function cv2.imshow(). This snippet gives the black and white image on the RTSP Stream link . Output is given below link [ output of FFmpeg link].
I have tried the ffplay command but it gives the direct image . i am not able to access the frame or apply the image processing.

  


  Output of FFMPEG

  


  import cv2
import subprocess as sp
command = [ 'C:/ffmpeg/ffmpeg.exe',
            '-i', 'rtsp://192.168.1.12/media/video2',
            '-f', 'image2pipe',
            '-pix_fmt', 'rgb24',
            '-vcodec', 'rawvideo', '-']


import numpy
pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
while True:
    raw_image = pipe.stdout.read(420*360*3)
   # transform the byte read into a numpy array
    image =  numpy.fromstring(raw_image, dtype='uint8')
    image = image.reshape((360,420,3))
    cv2.imshow('hello',image)
    cv2.waitKey(1)
    # throw away the data in the pipe's buffer.
    pipe.stdout.flush()


  


• avformat/srtdec : speed up probing

  4 septembre 2014, par wm4

  avformat/srtdec : speed up probing
  

  • [DH] libavformat/srtdec.c