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• 'arecord' works but FFMPEG 'cannot open audio device'

  16 mai 2020, par kwithnail

  On my Linux-based QNAP NAS, I can successfully record my Loopback audio device using :

  



  # arecord -D default:CARD=Loopback test.wav


  



  However, FFMPEG cannot use this same audio device. It returns :

  



      [alsa @ 0x5a45880] cannot open audio device hw:default:CARD=Loopback (No such file or directory)
hw:default:CARD=Loopback: Input/output error


  



  I've also tried any number of hw: options in FFMPEG. For what it's worth, the arecord -l command returns :

  



  **** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC262 Analog [ALC262 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 1/1
  Subdevice #0: subdevice #0


  



  arecord -L returns :

  



  [~] # arecord -L
null
    Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=PCH
    HDA Intel PCH, ALC262 Analog
    Default Audio Device
front:CARD=PCH,DEV=0
    HDA Intel PCH, ALC262 Analog
    Front speakers
sysdefault:CARD=Loopback
    Loopback, Loopback PCM
    Default Audio Device
front:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    Front speakers
surround21:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Loopback,DEV=0
    Loopback, Loopback PCM
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers


  



  FFMPEG command and response is :

  



  [~] # /share/CACHEDEV1_DATA/.qpkg/ffmpeg/ffmpeg -f alsa -i hw:default:CARD=Loopback test.mp3
ffmpeg version 4.2.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
ALSA lib ../../../src/pcm/pcm.c:2564:(snd_pcm_open_noupdate) Unknown PCM hw:default:CARD=Loopback
[alsa @ 0x5f64800] cannot open audio device hw:default:CARD=Loopback (No such file or directory)
hw:default:CARD=Loopback: Input/output error


  



  FFMPEG -sources alsa gives :

  



  [~] # /share/CACHEDEV1_DATA/.qpkg/ffmpeg/ffmpeg -sources alsa
ffmpeg version 4.2.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Auto-detected sources for alsa:
ALSA lib ../../../src/control/control.c:1375:(snd_ctl_open_noupdate) Invalid CTL hw:0
Cannot list sources.


  



  Can anyone shed some light on why this is impossible in FFMPEG and suggest what I'm doing wrong here ? FFMPEG includes the ALSA module, and is version 4.2.1. Thanks !

  


• Mirror not found when trying to install FFMPEG on CENTOS7

  31 octobre 2016, par Peter

  I’m on a dedicated server with Root access. not familiar with servers. Im trying to install FFMpeg on my server but following online instructions I’m getting errors can’t figure out how to solve it. So any light on this will be very appreciated.

  [root@ns335004 ~]# yum update
  
  base                                                                                                           | 3.6 kB  00:00:00     
  
  http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
  
  Trying other mirror.
  
  To address this issue please refer to the below knowledge base article 
  
  
  
  https://access.redhat.com/articles/1320623
  
  
  
  If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/
  
  
  
  
  
  
  
   One of the configured repositories failed (DAG RPM Repository),
  
   and yum doesn't have enough cached data to continue. At this point the only
  
   safe thing yum can do is fail. There are a few ways to work "fix" this:
  
  
  
       1. Contact the upstream for the repository and get them to fix the problem.
  
  
  
       2. Reconfigure the baseurl/etc. for the repository, to point to a working
  
          upstream. This is most often useful if you are using a newer
  
          distribution release than is supported by the repository (and the
  
          packages for the previous distribution release still work).
  
  
  
       3. Disable the repository, so yum won't use it by default. Yum will then
  
          just ignore the repository until you permanently enable it again or use
  
          --enablerepo for temporary usage:
  
  
  
              yum-config-manager --disable dag
  
  
  
       4. Configure the failing repository to be skipped, if it is unavailable.
  
          Note that yum will try to contact the repo. when it runs most commands,
  
          so will have to try and fail each time (and thus. yum will be be much
  
          slower). If it is a very temporary problem though, this is often a nice
  
          compromise:
  
  
  
              yum-config-manager --save --setopt=dag.skip_if_unavailable=true
  
  
  
  failure: repodata/repomd.xml from dag: [Errno 256] No more mirrors to try.
  
  http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found

  repolist

  [root@ns335004 ~]# yum repolist all
  
  http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
  
  Trying other mirror.
  
  To address this issue please refer to the below knowledge base article 
  
  
  
  https://access.redhat.com/articles/1320623
  
  
  
  If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/
  
  
  
  http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
  
  Trying other mirror.
  
  repo id                                  repo name                                                                     status
  
  C7.0.1406-base/x86_64                    CentOS-7.0.1406 - Base                                                        disabled
  
  C7.0.1406-centosplus/x86_64              CentOS-7.0.1406 - CentOSPlus                                                  disabled
  
  C7.0.1406-extras/x86_64                  CentOS-7.0.1406 - Extras                                                      disabled
  
  C7.0.1406-fasttrack/x86_64               CentOS-7.0.1406 - CentOSPlus                                                  disabled
  
  C7.0.1406-updates/x86_64                 CentOS-7.0.1406 - Updates                                                     disabled
  
  C7.1.1503-base/x86_64                    CentOS-7.1.1503 - Base                                                        disabled
  
  C7.1.1503-centosplus/x86_64              CentOS-7.1.1503 - CentOSPlus                                                  disabled
  
  C7.1.1503-extras/x86_64                  CentOS-7.1.1503 - Extras                                                      disabled
  
  C7.1.1503-fasttrack/x86_64               CentOS-7.1.1503 - CentOSPlus                                                  disabled
  
  C7.1.1503-updates/x86_64                 CentOS-7.1.1503 - Updates                                                     disabled
  
  base/7/x86_64                            CentOS-7 - Base                                                               enabled:  9,007
  
  base-debuginfo/x86_64                    CentOS-7 - Debuginfo                                                          disabled
  
  base-source/7                            CentOS-7 - Base Sources                                                       disabled
  
  c7-media                                 CentOS-7 - Media                                                              disabled
  
  centosplus/7/x86_64                      CentOS-7 - Plus                                                               disabled
  
  centosplus-source/7                      CentOS-7 - Plus Sources                                                       disabled
  
  cr/7/x86_64                              CentOS-7 - cr                                                                 disabled
  
  dag/7/x86_64                             DAG RPM Repository                                                            enabled:      0
  
  epel/x86_64                              Extra Packages for Enterprise Linux 7 - x86_64                                enabled: 10,764
  
  epel-debuginfo/x86_64                    Extra Packages for Enterprise Linux 7 - x86_64 - Debug                        disabled
  
  epel-source/x86_64                       Extra Packages for Enterprise Linux 7 - x86_64 - Source                       disabled
  
  epel-testing/x86_64                      Extra Packages for Enterprise Linux 7 - Testing - x86_64                      disabled
  
  epel-testing-debuginfo/x86_64            Extra Packages for Enterprise Linux 7 - Testing - x86_64 - Debug              disabled
  
  epel-testing-source/x86_64               Extra Packages for Enterprise Linux 7 - Testing - x86_64 - Source             disabled
  
  extras/7/x86_64                          CentOS-7 - Extras                                                             enabled:    393
  
  extras-source/7                          CentOS-7 - Extras Sources                                                     disabled
  
  fasttrack/7/x86_64                       CentOS-7 - fasttrack                                                          disabled
  
  nux-dextop/x86_64                        Nux.Ro RPMs for general desktop use                                           disabled
  
  nux-dextop-testing/x86_64                Nux.Ro RPMs for general desktop use - testing                                 disabled
  
  plesk-php-5.6                            PHP v 5.6 for Plesk - x86_64                                                  enabled:     31
  
  plesk-php-7.0                            PHP v 7.0 for Plesk - x86_64                                                  enabled:     28
  
  updates/7/x86_64                         CentOS-7 - Updates                                                            enabled:  2,560
  
  updates-source/7                         CentOS-7 - Updates Sources                                                    disabled
  
  repolist: 22,783

  I also tried :

  sudo yum clean metadata
  
  sudo yum clean all

  But still having same 404 Error.

  Thanks.

• Decoding audio w/ ffmpeg error on Android

  14 août 2012, par stranded

  Well, I knew I was going out of my comfort zone when I decided to try and decode audio using ffmpeg on Android but now I will have to admit that I'm stranded.
  It took me many days to just build ffmpeg for Android. Roman's10 guide did not work for me but finally things started looking up, thanks to this tutorial. So because of Dmitry's help I managed to build the armeabi version (not armeabi-v7) for my phone (LG P500) and everything basic works.

  But when I try to use avcodec_decode_audio3() things go downhill :( Never before have I felt so close to making things work (after all it seems to be only one line that is troublesome)
  but unable to though. I've read many questions here on SO that have brought me closer to the goal. Googling, on the other hand, has had limited results - making questions here the only fruit.

  Yes, I know ! I ramble. But I can't help it, I'm only trying to explain in detail where I'm stuck and how I got there. So without further ado I bring you the code :

  NATIVE CODE :

  #include 
  
  #include <android></android>log.h>
  
  
  
  #include "libavcodec/avcodec.h"
  
  #include "libavformat/avformat.h"
  
  
  
  #define LOG_TAG "mylib"
  
  #define LOGI(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
  
  #define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
  
  
  
  #define INBUFF_SIZE 4096
  
  #define AUDIO_INBUFF 20480
  
  #define AUDIO_REFILL_SIZE 4096
  
  
  
  jint Java_com_nothingworks_for_me_MainActivity_decode(JNIEnv * env, jobject this, jstring jfilename){
  
      const char *filename = (*env)->GetStringUTFChars(env, jfilename, NULL);
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int audioStream;
  
      int out_size, len, i;
  
      FILE *f, *outfile;
  
      uint8_t *outbuf;
  
      uint8_t inbuf[AUDIO_INBUFF + FF_INPUT_BUFFER_PADDING_SIZE];
  
      AVPacket avpkt;
  
      AVFormatContext *pFormatCtx;
  
  
  
      av_register_all();
  
      avcodec_init();
  
      av_init_packet(&amp;avpkt);
  
  
  
      if(av_open_input_file(&amp;pFormatCtx, filename, NULL, 0, NULL)!=0)
  
      {
  
          LOGE("Can&#39;t open file &#39;%s&#39;\n", filename);
  
          return 1;
  
      }
  
      else
  
      {
  
          LOGI("File was opened\n");
  
          LOGI("File &#39;%s&#39;, Codec %s",
  
                  pFormatCtx->filename,
  
                  pFormatCtx->iformat->name
  
          );
  
      }
  
  
  
      if (av_find_stream_info(pFormatCtx) &lt; 0){
  
          LOGE("Can&#39;t find stream info");
  
      }
  
      audioStream = -1;
  
      for (i = 0; i &lt; pFormatCtx->nb_streams; i++) {
  
          if (pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO) {
  
              audioStream = i;
  
              break;
  
          }
  
      }
  
  
  
      if (audioStream == -1) {
  
          LOGE("Didn&#39;t find stream!");
  
      }
  
      c = pFormatCtx->streams[audioStream]->codec;
  
  
  
      codec = avcodec_find_decoder(c->codec_id);
  
      if (!codec) {
  
          LOGE("Unsupported Codec!");
  
      }
  
  
  
      c= avcodec_alloc_context();
  
  
  
      /* open it */
  
      if (avcodec_open(c, codec) &lt; 0) {
  
          LOGE("Can&#39;t open codec");
  
          exit(1);
  
      }
  
  
  
      outbuf = av_malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE * 2);
  
  
  
      f = fopen(filename, "rb");
  
      if (!f) {
  
          LOGE("Can&#39;t open file");
  
          exit(1);
  
      }
  
  
  
      /* decode until eof */
  
      avpkt.data = inbuf;
  
      avpkt.size = fread(inbuf, 1, AUDIO_INBUFF, f);
  
      LOGI("avpkt.size %d", avpkt.size);
  
  
  
      while (avpkt.size > 0) {
  
          out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2; 

  THINGS GO WRONG HERE ! avcodec_decode_audio3() The code continues from ▲ to ▼ :

          len = avcodec_decode_audio3(c, (int16_t *)outbuf, &out_size, &avpkt);
  
          LOGI("data_size %d len %d", out_size, len);
  
          if (len < 0) {
  
              LOGE("Error while decoding");
  
              exit(1);
  
          }
  
          if (out_size > 0) {
  
  
  
          }
  
          avpkt.size -= len;
  
          avpkt.data += len;
  
          if (avpkt.size < AUDIO_REFILL_SIZE) {
  
              /* Refill the input buffer, to avoid trying to decode
  
               * incomplete frames. Instead of this, one could also use
  
               * a parser, or use a proper container format through
  
               * libavformat. */
  
              memmove(inbuf, avpkt.data, avpkt.size);
  
              avpkt.data = inbuf;
  
              len = fread(avpkt.data + avpkt.size, 1,
  
                      AUDIO_INBUFF - avpkt.size, f);
  
              if (len > 0)
  
                  avpkt.size += len;
  
          }
  
      }
  
      fclose(f);
  
      free(outbuf);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      return 0;
  
  }

  ---

  What happens is that avcodec_decode_audio3() returns -1 and that's pretty much it :(
  I have no idea what to do next. I can't find much info about this and I only started fiddling with C less than two weeks ago so your guidance is my only hope now [play dramatic sound]. Hope someone can shed a little light on this mystery.

  Ohh ! And the native code is some kind of a hybrid between what I have found here on SO, like this and this, and the ffmpeg example. On the java side I only have a call to this native method and pass it string which is the path to a MP3 song on my droid. I don't use AudioTrack or anything else in my java code yet 'cause I'm only trying to get the decoding to work for now.

  -Drama Queen OUT !