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• How can I write SAPI audio stream to stdout in VBScript ?

  10 mai 2015, par Ravenstine

  I have this VBScript that will take some text from the command line and dictate it to a wav file using MS SAPI.

  Const SAFT48kHz16BitStereo = 39
  
  Const SSFMCreateForWrite = 3
  
  
  
  Set oFileStream = CreateObject("SAPI.SpFileStream")
  
  oFileStream.Format.Type = SAFT48kHz16BitStereo
  
  oFileStream.Open "C:\sample.wav", SSFMCreateForWrite
  
  
  
  Set Sapi = CreateObject("SAPI.SpVoice") 
  
  Set Sapi.voice = Sapi.GetVoices("Name=Microsoft Sam", "Language=409").Item(0)
  
  Sapi.volume = 100
  
  Sapi.rate = 3
  
  Set Sapi.AudioOutputStream = oFileStream
  
  Set args = Wscript.Arguments
  
  Sapi.Speak(args.item(0))

  Is it possible to, instead of write the audio to a file, write it to standard output ? I’d like to be able to pipe the audio directly to FFMpeg without writing to the file system.

• Warning VSP2005 & Error VSP1048 when instrumenting C++ code dynamically linked to FFMPEG

  6 mai 2015, par TTJG

  I am trying to profile my project with the Instrumentation profiler of Visual Studio 2013 Ultimate. I have a 64bit C++ project which is dynamically linked to FFMPEG. However, the profiler is giving me the following error Error VSP1048: Internal instrumentation error. I don’t want to profile FFMPEG but only analyze the performance of my code. I downloaded the pre-built FFMPEG libs from this site ffmpeg.zeranoe.com/builds/. The project is also linking against Boost, live555 and x264. It is running and debugging fine. The full output of the profiler is :

  Profiling started.
  
  Instrumenting ...\Player.exe in place
  
  Info VSP3049: Small functions will be excluded from instrumentation.
  
  Microsoft (R) VSInstr Post-Link Instrumentation 12.0.21005 x64
  
  Copyright (C) Microsoft Corp. All rights reserved.
  
  Warning VSP2005: Internal instrumentation warning: The object '...\ffmpeg-20150506-git-a2190de-win64-dev\lib\avutil.lib(dbyqh.o)' was built without debug information.
  
  File to Process:
  
  \Player.exe --> ...\Player.exe
  
  Original file backed up to ...\Player.exe.orig
  
  Warning VSP2005: Internal instrumentation warning: The object '...\ffmpeg-20150506-git-a2190de-win64-dev\lib\avutil.lib(dbyqh.o)' was built without debug information.
  
  Error VSP1048: Internal instrumentation error.
  
  PRF0002: Instrumentation failed with these options: /u "...\Player.exe"   /excludesmallfuncs.  Please check the output window for additional details.
  
  Data written to ...\Player150506.vsp.
  
  Profiling finished.
  
  File contains no data buffers
  
  File contains no data buffers
  
  Analysis failed
  
  Profiling complete.

  Any ideas how this could be solved ? I have found very little about this issue on the Internet.

• How to parallelize this for loop for rapidly converting YUV422 to RGB888 ?

  16 avril 2015, par vineet

  I am using v4l2 api to grab images from a Microsoft Lifecam and then transferring these images over TCP to a remote computer. I am also encoding the video frames into a MPEG2VIDEO using ffmpeg API. These recorded videos play too fast which is probably because not enough frames have been captured and due to incorrect FPS settings.

  The following is the code which converts a YUV422 source to a RGB888 image. This code fragment is the bottleneck in my code as it takes nearly 100 - 150 ms to execute which means I can’t log more than 6 - 10 FPS at 1280 x 720 resolution. The CPU usage is 100% as well.

  for (int line = 0; line < image_height; line++) {
  
      for (int column = 0; column < image_width; column++) {
  
          *dst++ = CLAMP((double)*py + 1.402*((double)*pv - 128.0));                                                  // R - first byte           
  
          *dst++ = CLAMP((double)*py - 0.344*((double)*pu - 128.0) - 0.714*((double)*pv - 128.0));    // G - next byte
  
          *dst++ = CLAMP((double)*py + 1.772*((double)*pu - 128.0));                                                            // B - next byte
  
  
  
          vid_frame->data[0][line * frame->linesize[0] + column] = *py; 
  
  
  
          // increment py, pu, pv here
  
  
  
      }

  ’dst’ is then compressed as jpeg and sent over TCP and ’vid_frame’ is saved to the disk.

  How can I make this code fragment faster so that I can get atleast 30 FPS at 1280x720 resolution as compared to the present 5-6 FPS ?

  I’ve tried parallelizing the for loop across three threads using p_thread, processing one third of the rows in each thread.

  for (int line = 0; line < image_height/3; line++) // thread 1
  
  for (int line = image_height/3; line < 2*image_height/3; line++) // thread 2
  
  for (int line = 2*image_height/3; line < image_height; line++) // thread 3

  This gave me only a minor improvement of 20-30 milliseconds per frame.
  What would be the best way to parallelize such loops ? Can I use GPU computing or something like OpenMP ? Say spwaning some 100 threads to do the calculations ?

  I also noticed higher frame rates with my laptop webcam as compared to the Microsoft USB Lifecam.

  Here are other details :

  • Ubuntu 12.04, ffmpeg 2.6
  • AMG-A8 quad core processor with 6GB RAM
  • Encoder settings :
    • codec : AV_CODEC_ID_MPEG2VIDEO
    • bitrate : 4000000
    • time_base : (AVRational)1, 20
    • pix_fmt : AV_PIX_FMT_YUV420P
    • gop : 10
    • max_b_frames : 1