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• encode blackmagic decklink audio frame to aac using FFMPEG api

  14 juillet 2021, par Illikkal

  Trying to encode raw audio(pcms16le and 1920 samples) from blackmagic decklink card to aac using ffmpeg api.How to convert this sSAMPLE_FMT_S16 1920 samples to SAMPLE_FMT_FLTP 1024 samples for aac encoding

  


• modprobe snd-dummy on linux server, ffmpeg -f alsa is recording noise

  20 mars 2021, par booksword

  Some people say that the parameter fake_buffer can remove the noise, but I tried it and there is still noise

  


  


  modprobe snd-dummy fake_buffer=0

  


  


  #modprobe snd-dummy fake_buffer=0 
# lsmod |grep snd
snd_dummy              24576  0
snd_pcm_oss            61440  0
snd_mixer_oss          28672  1 snd_pcm_oss
snd_pcm               118784  2 snd_pcm_oss,snd_dummy
snd_timer              36864  1 snd_pcm
snd                    94208  5 snd_timer,snd_pcm_oss,snd_pcm,snd_dummy,snd_mixer_oss
soundcore              16384  1 snd
# modinfo snd_dummy
filename:       /lib/modules/4.14.129-bbrplus/kernel/sound/drivers/snd-dummy.ko
license:        GPL
description:    Dummy soundcard (/dev/null)
author:         Jaroslav Kysela <perex@perex.cz>
depends:        snd-pcm,snd
retpoline:      Y
intree:         Y
name:           snd_dummy
vermagic:       4.14.129-bbrplus SMP mod_unload modversions 
parm:           index:Index value for dummy soundcard. (array of int)
parm:           id:ID string for dummy soundcard. (array of charp)
parm:           enable:Enable this dummy soundcard. (array of bool)
parm:           model:Soundcard model. (array of charp)
parm:           pcm_devs:PCM devices # (0-4) for dummy driver. (array of int)
parm:           pcm_substreams:PCM substreams # (1-128) for dummy driver. (array of int)
parm:           fake_buffer:Fake buffer allocations. (bool)
parm:           hrtimer:Use hrtimer as the timer source. (bool)

#aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
pulse
    PulseAudio Sound Server
dummy
default:CARD=Dummy
    Dummy, Dummy PCM
    Default Audio Device
sysdefault:CARD=Dummy
    Dummy, Dummy PCM
    Default Audio Device
dmix:CARD=Dummy,DEV=0
    Dummy, Dummy PCM
    Direct sample mixing device
dsnoop:CARD=Dummy,DEV=0
    Dummy, Dummy PCM
    Direct sample snooping device
hw:CARD=Dummy,DEV=0
    Dummy, Dummy PCM
    Direct hardware device without any conversions
plughw:CARD=Dummy,DEV=0
    Dummy, Dummy PCM
    Hardware device with all software conversions


# ffmpeg -f alsa  -i hw:0 -t 5  /dev/shm/out.mp3 -y
ffmpeg version 3.4.8-0ubuntu0.2 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/usr --extra-version=0ubuntu0.2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, alsa, from 'hw:0':
  Duration: N/A, start: 1616225206.353453, bitrate: 1536 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to '/dev/shm/out.mp3':
  Metadata:
    TSSE            : Lavf57.83.100
    Stream #0:0: Audio: mp3 (libmp3lame), 48000 Hz, stereo, s16p
    Metadata:
      encoder         : Lavc57.107.100 libmp3lame
size=      79kB time=00:00:05.01 bitrate= 129.0kbits/s speed=   1x     
video:0kB audio:79kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.293899%




  


  i use alsamixer to set all Volume to 0 ,and there is still noise
I searched in google for a long time and did not find other people have this problem , where am I doing it wrong

  


• How to download .ism files protected by DRM (Widevine or IIS Smoth Streaming)

  16 septembre 2019, par Foopy7774

  I’m struggling to download a video which is protected by DRM or something else (idk)...I tried to download it by using VLC, ismdownloader, ffmpeg and youtube-dl but the video seems encrypted. There bound to be a way to do it, given that Chrome is able to read it...

  I’ve seen that they are using Widevine or IIS Smooth Streaming, I don’t really know...but if you can’t answer my post, can you atleast set me on the right path by telling me :
  What they use ? Widevine ? IIS Smooth Streaming ? Both ?

  Video link : https://www.mycanal.fr/actualites/balance-ton-post-ca-continue-emission-du-12-sept-2019/h/12299856_50013
  Manifest file :
  https://hssodcplus-s.akamaihd.net/ondemand/playready/canalplus/d8/d8_1205541_1_D8/93653/d8-1205541-1-D8.ism/manifest if you can’t access to it : https://pastebin.com/20mgS9C4

  Here is what I get using VLC : https://i.imgur.com/u3mWrWg.gifv

  Thanks !