15th Feb 2007

Video Editing Production and Camcorders

Adding Sounds to a Video Production

Audio mixers, including the audio mixer on the Videonics Sound Effects Mixer and Video Equalizer, can be used to add sounds to a videotape. This application note describes how. It is oriented to these two units but the instructions are easily adapted to any other audio mixer.

Audio mixing — what is it and why?

A production’s sound track has a deeper effect on the apparent quality of a production than most people realize. A good sound track can evoke emotions, clarify the action, and shift the mood. It can make the difference between an average production and an outstanding one. This important aspect of video making is relatively simple yet is often underestimated by the beginner.

Simply put, audio mixing is the combining of music, sound effects, and narration (voice-over) with the sound on the original tape (called the native sound). However, replacing or adding to the sound on a videotape is complicated by the fact that unlike pro gear, consumer VCRs will not necessarily allow you to simply replace the sound without also re-recording the video. There are some fairly simple methods but first, you’ll need to understand a little detail….

How sound is recorded by VCRs and camcorders

VCRs and camcorders use three kinds of sound recording:

  1. Hi-fi or AFM sound is recorded along with the video. It has very high quality (approaching that of CDs) but can not be re-recorded without re-recording the video as well.
  2. A separate sound track, called the linear or non-hi-fi track, is recorded at the same time. It has the advantage that it can be re-recorded without affecting the video, if the recorder has a feature called audio dub. Some VCRs have the ability to play the hi-fi tracks alone, the linear track alone, or a 50-50 mix of the two. All hi-fi VCRs and camcorders simultaneously record the same sound on both tracks. Non-hi-fi machines record only on the linear track.
  3. A third kind of sound is used on some 8-mm and Hi8 units. PCM has quality similar to that provided by hi-fi or AFM but is recorded on a separate track, independent of the video. This means it has an advantage of both: It can be re-recorded without destroying the video, yet has quality suitable for music.

How to mix in new audio

There are three methods for changing the sound with consumer equipment:

  1. You can replace the sound or mix new sound with the old while you edit, using a separate audio mixer. The mixer has separate volume controls for each source so you can independently adjust voice from a microphone, music from a CD or tape player, and the native sound on the original tape.
    • On the Sound Effects Mixer and Video Equalizer, the control marked “VCR” will increase or decrease the volume of the sound on the original tape (called the “native” sound). The MUSIC control will vary the volume of whatever is plugged into the MUSIC inputs; and the MIC control will change the microphone. You can use these controls to balance the sources until you have the desired mix. The Sound Effects Mixer also adds its own sounds. These are mixed evenly into the music source.
    • The advantage of this method is that the final tape will have the correct mix on all its sound tracks and can therefore be heard correctly regardless of the sound features of the player. The disadvantage is that you need to mix the sound while each scene is recorded. Making music smoothly span from one scene to the next is next to impossible but narration can be applied scene by scene.
  2. If your VCR has the audio dub feature, you can add sound to the finished tape’s linear or PCM track. When the tape is played, you can select which track or tracks you want to hear, assuming that the player is capable of playing the tracks. The sound quality of the linear track is a possible limitation.
  3. You can also use audio dub to re-record the linear or PCM track of the original before you edit.

Music

“Scoring a production” is easy. Think about the production you are making and some tune will pop into your head that you feel fits. Is the production suspenseful? If so, try organ music. If it’s travel, try Hawaiian guitars.

One problem is where to find music. Keep in mind that almost all commercially recorded music is protected by copyright. Professionals license the music they use. They generally buy large collections and pay the publisher a fee for each “drop.” (A drop refers to when the collections came on phonograph records and there was a fee each time the needle was dropped on the record. LPs are gone, but the drop term remains.)

You can buy licensed music from a variety of sources. Available as CDs or tapes, these collections come with a license that allows you to use the music in your productions. You are permitted to use the music on these collections as often as you like — unlike with the professional service, there is no drop charge.

Don’t overlook local musicians. You may know a band or a talented individual who can record custom music for a small fee or in exchange for credit at the end.

Voice-over

Narration can give your story a framework. It can tell what has happened, bring the viewer up to date, set the time or place (“I found myself on the famous street of dreams”), or tell what a character is thinking (“I wonder what’s in that closet?”). Narration can also be used to guide an unfolding story (“I woke up with a five-knuckle lump on my jaw and a piano-sized headache. Louis obviously wanted to teach me to keep my nose outta his business.”)

Sound Effects

Almost everything on television has audio special effects added to provide “realism.” Every punch thrown, every outdoor vista, every smoking getaway car needs sound to help us believe the action. Professionals employ a “foley artist” to “sweeten” the sound track. Very little native sound is used — the foley artist replaces even footsteps with studio-produced sounds!

Native sounds satisfy the bulk of the home producer’s needs. But there will be times when the recorded sounds need some help, or when you’d like to add a totally new sound. You can even use inappropriate or exaggerated sounds for comic effect.

To do this, you can record a sound with a microphone, use the Sound Effects Mixer with its built-in digital sound effects (about $180), or purchase sound effects on CDs or tapes (typically $15-50).

Connections

To add sound as you re-record or edit, you will need two VCRs: A play-VCR is used to play the original tape. A recording VCR is used to record the resulting signal on a blank tape. Connect the AUDIO OUT connections to the recording VCR’s AUDIO IN connections. Connect a video signal from the play-VCR to the recording VCR. If the audio mixer has VIDEO IN and OUT connections, you should use them as well. (In the case of the Sound Effects Mixer, the VIDEO connections are there for convenience — whatever is plugged into VIDEO IN will be passed directly to VIDEO OUT. The video signal is not modified.)

Line In

Each VCR is equipped with some method for determining whether it is recording its own tuner (that is, a TV broadcast) or an external video source (that is, whatever is plugged into its VIDEO and AUDIO inputs).

Be sure to switch the VCR’s input so it is recording the external source. If you don’t do this, the VCR will record whatever channel it is set to.

On most units, there is a switch marked LINE/TUNER. Set the switch to LINE. On others, the switch may be marked AUX or EXT. Some require that you set it to a special channel and still others switch to external whenever you plug a cable into the IN jacks. See your VCR manual for specifics.

Starting the recording

Once everything is connected, press play on the play-VCR and record on the record-VCR. As the tape plays, vary the audio controls so the desired sound is recorded. Headphones, plugged into the record VCR or into the audio mixer, will help you monitor the results.

Editing

All this can also be done while editing with an edit controller, such as Videonics Thumbs Up or Edit Suite.

Connect the audio mixer between the play-VCR and the editor — not between the editor and the recorder. Then simply adjust the controls as the editor records the scenes of interest. If you prefer not to wait for the editor to locate the scenes, you can set the editor to record one scene at a time.

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