Digital Home Thoughts: From Home Movies to Hollywood Blockbusters with Adobe Premiere Pro

Eh? Speak Up, Laddie!
It isn’t only on the video side of a project that Premiere Pro has been improved – there have been significant improvements in the way that audio is handled as well. Probably the first change you’ll notice is when you import any audio into a project – Premiere Pro immediately starts conforming that audio. What Premiere is doing here is re-sampling the audio so that all audio in the project is at the same sample rate and bit size. By doing this, it ensures that the maximum quality is achieved. However, it is at the expense of additional disc space so you will need more than ever now.

Next on the list of changes is the way that audio tracks are handled. With previous versions, you had stereo tracks and their output was mixed together based on the overall volume. With this version, you can have a mixture of mono, stereo and 5.1 tracks. In addition, there is now the concept of a master track. The idea here is that the various audio tracks are routed and mixed into the master track. The properties of the master track are set when you create the sequence. By default, the initial sequence will have a stereo master track but it is easy to change that when you create the project, or you can create new sequences with different audio settings.

Clearly, with such track flexibility, you need a mixer to match and Adobe have delivered. Figure 24 shows the mixer for a project that contains a mono track, a stereo track, a 5.1 track and a stereo master track. You might be wondering what Premiere Pro does with all of the 5.1 surround information if you've only got a stereo output track. The answer can be seen in Figure 25, which is an excerpt from the Preferences window. Essentially, you can take just the front channels or mix the front and rear, the front and LFE (low frequency effects), or the whole lot (front + rear + LFE). The one downside is that this is set in the preferences (which is global to Premiere Pro) rather than the project settings. The reason why this could be a problem is that if you give all of the project files to someone else, they might get a different outcome if their 5.1 mixdown preference is different from yours.


Figure 24: Audio mixer with stereo master track. Click on the image for the full size image. (29KB)


Figure 25: Mixing 5.1 down to fewer tracks.

If, on the other hand, your master track is 5.1, then life gets really interesting, as can be seen in Figure 26. The track meters almost look identical to Figure 24, except that the master track has more of them. The biggest different can be seen just above the mono & stereo tracks. Instead of simple left/right panning knobs, you've got a more complicated panning interface. This allows you to precisely position the output of that track within the 5.1 arena. The small knobs to the left of the panning space allow you to control how much that track contributes to the centre and LFE channels.


Figure 26: Same track configuration but 5.1 master track. Click on the image for the full size image. (13KB)

The icons just above each of the tracks allow you to mute the track, "solo" the track (so everything else is muted) and to record over the track (not available for 5.1 tracks). Electing to record over a track gives us evidence of the next improvement in Premiere's audio capabilities – support for ASIO. Audio Stream In/Out was developed by Steinberg as a driver interface for delivering low-latency transfer of digital audio. By supporting ASIO, Premiere Pro is also able to record from multiple sources simultaneously on separate tracks. Clicking on the microphone track enables that track for recording and you can then choose the source, as can be seen in Figure 27. It should be realised that this menu is presenting different combinations of the mono sources available on my Sound Blaster Audigy 2 card. Not all of these permutations are at all sensible. For example, choosing any of the mix inputs results in feedback because Premiere then plays that back when it feeds into the mix which then gets recorded by Premiere which … you get the idea 8O


Figure 27: Different stereo input permutations.

It is significant, though, that you can set Premiere up to capture multiple tracks of audio at once – truly a leap forwards from previous versions!

Having got the audio into your project, what can you do with it then? Well, this is where it gets a little bit more complicated. The reason for the complication is because you can manipulate the audio in two different ways – one via the timeline and the other via the audio mixer. Now, that doesn't sound complicated, until you realise that if you add an audio effect to the timeline, it doesn't appear in the audio mixer, and vice-versa. I guess Adobe has a reason for the software working this way but, for now, my recommendation would be to use one method or the other and then stick to it. Using the timeline gives you visual & fine control over the settings with keyframes. Using the audio mixer allows you to use a more organic process for changing the values, i.e. twiddling graphical knobs whilst the playback takes place. The choice is entirely up to you. There are a few effects that can only be applied to the timeline, e.g. swap channels, fill left & fill right – all of which only apply to stereo tracks.

Premiere comes with 17 effects that can be used in the mixer – and they are VST effects! Virtual Studio Technology plug-ins allow you to extend the audio capabilities beyond the ones that are included – and they aren't bad either! Invert, delay, multitap delay, lowpass, highpass, bandpass, notch, parametric EQ, bass, treble, channel volume, denoiser, dynamics, EQ, multiband compressor, pitch shifter and reverb – and all of them are available for mono, stereo AND 5.1 tracks (with the exception of channel volume which isn't available for mono tracks). Each audio track can have five effects stacked within the audio mixer. This limit doesn't apply if you add the effects to the timeline.

The final area of audio manipulation within the audio mixer interface is the topic of submixes. As with the tracks, you can have mono, stereo and 5.1 submixes. They allow you to send the output of previous tracks or mixes through a submix and then on to another submix or to the master track. Indeed, a track can be sent to the master track and to a submix, thus allowing you to determine how much influence the submix has over the original track – what is called the wet/dry mix.

If you've ever tried to sync audio with video before, you might have been frustrated by the limitations of only being able to get down to the frame level (25 frames per second with PAL and 29.97 frames per second with NTSC). That too has been fixed by a new feature in Premiere Pro – you can switch the timeline units between frames and audio units. In the latter, you can get the timeline to work in terms of the sample rate or in milliseconds.