Tag Archives: sound

what’s going on with the pc sound playback and recording

Here is a nice graph showing how all the sound sources are take in and mixed, and recorded on the pc:

For more details, can dig in here: http://en.wikipedia.org/wiki/Sound_card_mixer

The article also mentioned this:

Starting from Windows Vista and 7 new sound API model was introduced. There is no stereo mix or mono mix. Instead every playback device can be opened in loopback recording mode, so you can record what you hear from your speakers, headphones, digital output etc. Even if your audio card does not support it, Windows will emulate this functionality.

Seems like can record without a mixer, need some test to confirm this. And it does mention a list of software can recorder the sound without a sound card mixer:

Software for recording without Sound card mixer on Windows

* Freecorder 4 (freeware)
* Replay Music,
* Replay Media Catcher,
* Replay AV,
* Replay Video Capture,
* WM Capture
* VirtualAudioCable

Update to Free Mp3 Recorder 1.1

This is an update to the Free Mp3 Recorder 1.0.

The change in this version are: add the device (sound card) selector and a button to launch recording source dialog to select to record from microphone, mixer or other input.

Here is the updated screenshot:

It’s totally free, download now and start using it:

And if you need more features, please leave a comment below.

View the waveform with Pc Audio Visualizer

Pc Audio Visualizer is a  freeware/software to visualize the audio played on the pc. It takes audio from sound card so any audio played on the computer could be captured.
It displays the waveform of the sound, it’s fun to find out how the waveform behaves when different kind of sound is played: music, voice, song, music instrument, etc…

To get started

It’s designed to be running when you start it. If it’s not, you can select the device from the settings section and choose the source of the audio feed.

The FPS (frame per second) is about how many sample of sound to capture a second, for each sample it captures, it will display a pixel wide bar on the waveform screen as you see. You can drag over or simply use up/down ticker to set a value you want, feel free adjust and would be fun.

Stop button will flip the running and stop status of the waveform display.


  1. Waveform visualizer of left/right channel
  2. Device selection, and source selection to choose from “mixer” or “microphone” or other sources.
  3. Always on top to avoid to be covered by other window.
  4. Sample value display and vertical bar instant graphic display
  5. winxp, win7 supported

Download free and start using it now:
Need more features? Leave a comment below.

Record music/voice/audio with Free Mp3 Recorder

free mp3 recorder 1.1
To reocord sound from pc, whether it’s music, voice, or any audio, you can do it with a mp3 recorder. The idea is simple, record, save, and play back later. Let’s start this tutorial with this tool: Free Mp3 Recorder, it can be downloaded at the end of this post.

Free Mp3 Recorder is a free software (freeware) to record music or any other audio from your pc. It records the audio data played on the sound card, so any sound that can be played on the pc could be recorded. Including record music from online player which doesn’t have a download link or from your microphone when you are sing a song.

To get started

Click on the “Record Now” button it will start to record, you can select to record as Mp3 or Wav format. After finish, the recorded file will appear in the list below to let you play back to hear the effort. You can double click on the file name to play it or right click to select the menu options. Also a few button below to help you manage the play back and the recorded file list.


  1. You can record as Mp3/Wav format
  2. Specify the folder to save recorded files in
  3. Minimize to system tray to save screen space when you are doing recording
  4. A list to manage the recorded file, and right click menu supported on it
  5. Play back of the recorded audio
  6. Waveform display when recording

It’s totally free, download now and start using it:
Need more features? Leave a comment below.

What is decibel (dB) exactly?

First of all, decibel (dB) is the 10th of the bigger unit: bel
1 bel = 10 dB
Bel itself is the logarithm of the ratio of two values (in a kind of measurement),
ratio = v1/v2
bel = Math.Log10(ratio)
dB = 10 bel = 10 * Math.Log10(v1/v2)

The kind of measurement could be anything we want, voltage, current, temperature, and loudness of sound: When used with the loudness (sound pressure) of the sound, it is a ratio against roughly the sound of mosquito flying 3 meters away (2×10−5 Pa). Ratio your value with 2×10−5 and do log10, you get your bel value. What should care about it’s nature of: logarithm, and to what measure system and which value it is ratio against.
One good scenario is: when you plot something which will grow at a constant ratio of the total amount of itself, you will get a straight line.
This thing is really not intuitive when first see it. Keep it simple, it’s the Logarithmic scale of the ratio. I think should avoid using it, until you have fun of using it.