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• AAC encoder : refactor to resynchronize MIPS port

  15 septembre 2015, par Claudio Freire

  AAC encoder : refactor to resynchronize MIPS port
  This patch refactors the AAC coders to reuse code
  
  between the MIPS port and the regular, portable C code.
  
  There were two main functions that had to use
  
  hand-optimized versions of quantization code :
  
   - search_for_quantizers_twoloop
  
   - codebook_trellis_rate
  Those two were split into their own template header
  
  files so they can be inlined inside both the MIPS port
  
  and the generic code. In each context, they’ll link
  
  to their specialized implementations, and thus be
  
  optimized by the compiler.
  This approach I believe is better than maintaining
  
  several copies of each function. As past experience has
  
  proven, having to keep those in sync was error prone.
  
  In this way, they will remain in sync by default.
  Also, an implementation of the dequantized output
  
  argument for the optimized quantize_and_encode
  
  functions is included in the patch. While the current
  
  implementation of search_for_pred still isn’t using
  
  it, future iterations of main prediction probably will.
  
  It should not imply any measurable performance hit while
  
  not being used.
  

  • [DH] libavcodec/aaccoder.c
  • [DH] libavcodec/aaccoder_trellis.h
  • [DH] libavcodec/aaccoder_twoloop.h
  • [DH] libavcodec/aacenc_quantization.h
  • [DH] libavcodec/mips/aaccoder_mips.c
  • [DH] tests/fate/aac.mak

• Stream video from mobile camera to ffmpeg with NDK

  19 juillet 2013, par user2598307

  I need to create an application that captures video from a camera phone and send it to ffmpeg. Everything should be done only NDK level without SDK and Java
   The phone can be Root

  I am trying to open camera on my android device with this function "avformat_open_input()". I give this function a reference to device folder "/dev/msm_camera/" or "/dev/video0".

  I try like this :

        void Java_com_example_camera_MainActivity_testVideo(JNIEnv *env, jclass jc, jstring *filename)
  
  {
  
          av_register_all();
  
          avcodec_register_all();
  
          avformat_network_init();
  
          AVFormatContext* context = avformat_alloc_context();
  
          int video_stream_index,ret,i;
  
          AVInputFormat *input_format = NULL;
  
          const char formatName[] = "mpeg"; //for example mpeg
  
          const jbyte *str;
  
          str = (*env)->GetStringUTFChars(env, filename, NULL); //filename = "/dev/msm_camera"
  
          input_format = av_find_input_format(formatName);
  
          ret = avformat_open_input(&context, str, input_format, NULL);
  
          if (ret < 0){
  
             LOGE("Not open");
  
          }else{
  
             LOGI("camera was open");
  
          }
  
          if(avformat_find_stream_info(context,NULL) < 0){
  
             LOGE("No stream");
  
          }
  
          for(i =0;inb_streams;i++){
  
             if(context->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  
                 video_stream_index = i;
  
          }
  
          AVPacket packet;
  
          AVFrame *pFrame;
  
          av_init_packet(&packet);
  
          pFrame = avcodec_alloc_frame();
  
  
  
                  //open output file
  
          AVOutputFormat* fmt = av_guess_format("avi", NULL, NULL);
  
          AVFormatContext* outputContext = avformat_alloc_context();
  
          outputContext->oformat = fmt;
  
          avio_open2(&outputContext->pb, "/sdcard/test.avi", AVIO_FLAG_WRITE,NULL,NULL);
  
          AVStream* stream=NULL;
  
          AVFrame * frame;
  
          frame = avcodec_alloc_frame();
  
          int cnt = 0, frameDecoded;
  
  
  
                  //start reading packets from stream and write them to file
  
          av_read_play(context);
  
          while(av_read_frame(context,&packet)>=0 && cnt <300){ //Here function return -1
  
            if(packet.stream_index == video_stream_index)
  
            {//packet is video
  
              if(stream == NULL){
  
                 //create stream in file
  
                       stream = avformat_new_stream(outputContext,context->streams[video_stream_index]->codec->codec);
  
                       avcodec_copy_context(stream->codec,context->streams[video_stream_index]->codec);
  
                       stream->sample_aspect_ratio = context->streams[video_stream_index]->codec->sample_aspect_ratio;
  
                       avformat_write_header(outputContext,NULL);
  
               }
  
               packet.stream_index = stream->id;
  
               av_write_frame(outputContext,&packet);
  
               cnt++;
  
             }
  
             av_free_packet(&packet);
  
             av_init_packet(&packet);
  
          }
  
          av_read_pause(context);
  
          av_write_trailer(outputContext);
  
          avio_close(outputContext->pb);
  
          avformat_free_context(outputContext);         
  
   }

  As I know, we cannot get access to camera because my program has not root permission. So how I can give my program root permission ? Or how I can go around this problem ?

  I also tried to interact with the device driver using ioctl commands on C\C++, but I did not succeed because I have no experience and examples in Google.

  Thank you !!!

• Web camera Logitech and Linux

  8 novembre 2019, par Nick Saw

  I have Logitech C310 camera with the declared characteristics of 720p 30fps.

  If you connect the camera to windows, the recording is fully consistent with the stated 720p 30fps - the picture is clear.

  The challenge is to connect the same camera to OrangePI (server Armbian) and to save video files on it.

  The camera appears as /dev/video0.

  sudo ffmpeg -f v4l2 -s 1280x720 -i /dev/video0 output.wmv

  As a result, I get a crumbly picture with a frequency of 5 fps.

  Maybe I’m using ffmpeg incorrectly ? Please help me who has experience with Web cameras on Linux ...
  Thanks in advance.

  USB-camera configuration :

  v4l2-ctl --all --device=/dev/video0
  
  
  
  
  
  Driver Info (not using libv4l2):
  
          Driver name   : uvcvideo
  
          Card type     : UVC Camera (046d:081b)
  
          Bus info      : usb-1c1c000.usb-1
  
          Driver version: 4.14.18
  
          Capabilities  : 0x84200001
  
                  Video Capture
  
                  Streaming
  
                  Extended Pix Format
  
                  Device Capabilities
  
          Device Caps   : 0x04200001
  
                  Video Capture
  
                  Streaming
  
                  Extended Pix Format
  
  Priority: 2
  
  Video input : 0 (Camera 1: ok)
  
  Format Video Capture:
  
          Width/Height      : 1280/720
  
          Pixel Format      : 'YUYV'
  
          Field             : None
  
          Bytes per Line    : 2560
  
          Size Image        : 1843200
  
          Colorspace        : sRGB
  
          Transfer Function : Default
  
          YCbCr/HSV Encoding: Default
  
          Quantization      : Default
  
          Flags             :
  
  Crop Capability Video Capture:
  
          Bounds      : Left 0, Top 0, Width 1280, Height 720
  
          Default     : Left 0, Top 0, Width 1280, Height 720
  
          Pixel Aspect: 1/1
  
  Selection: crop_default, Left 0, Top 0, Width 1280, Height 720
  
  Selection: crop_bounds, Left 0, Top 0, Width 1280, Height 720
  
  Streaming Parameters Video Capture:
  
          Capabilities     : timeperframe
  
          Frames per second: 5.000 (5/1)
  
          Read buffers     : 0
  
                       brightness (int)    : min=0 max=255 step=1 default=128 value=128
  
                         contrast (int)    : min=0 max=255 step=1 default=32 value=32
  
                       saturation (int)    : min=0 max=255 step=1 default=32 value=32
  
   white_balance_temperature_auto (bool)   : default=1 value=1
  
                             gain (int)    : min=0 max=255 step=1 default=64 value=192
  
             power_line_frequency (menu)   : min=0 max=2 default=2 value=2
  
        white_balance_temperature (int)    : min=0 max=10000 step=10 default=4000 value=4610 flags=inactive
  
                        sharpness (int)    : min=0 max=255 step=1 default=24 value=24
  
           backlight_compensation (int)    : min=0 max=1 step=1 default=0 value=0
  
                    exposure_auto (menu)   : min=0 max=3 default=3 value=3
  
                exposure_absolute (int)    : min=1 max=10000 step=1 default=166 value=249 flags=inactive
  
           exposure_auto_priority (bool)   : default=0 value=1
  
                        led1_mode (menu)   : min=0 max=3 default=3 value=3
  
                   led1_frequency (int)    : min=0 max=131 step=1 default=0 value=0