Those new to filmmaking or those working with no budget will likely have to do all the audio post themselves, using whatever audio tools are available in their video editing software. At some stage though, if you are a professional or aspiring professional, you will want to hand over the audio post to audio post professionals. However, handing over your project to audio post professionals requires additional knowledge, to avoid a number of common pitfalls. So I'll go into a fair bit of detail and explanation in this post, to help you understand and avoid these pitfalls.
Firstly, it's worth understanding a little about audio files: The best choice for all concerned, the production sound mixer, picture editor and audio post team is the Broadcast Wav format (.wav), although MXF format is OK too. The broadcast Wav Format (BWF) was specifically designed for use in broadcast and film applications. The BWF has two storage areas, one for the digital audio data ("essence") and the other for numerical and text data ("metadata"). The most obvious use of metadata is to store the audio file name but there are many other fields of information stored in the metadata which, if used properly, can massively aid the audio post workflow. Some of the metadata fields are written automatically when recording, depnding on the recorder settings, for example; the sample rate, bit depth, file creation date, frame rate, duration, etc. Other fields need to be entered manually, for example; File name, Project, Sound Roll, Scene and take numbers, Circled, etc. This information should be added by the production sound mixer during recording. The Time Stamp fields are also incredibly useful! Ideally, the camera/s and the sound recorder are being fed time-code from a single common source. This will result in the original time stamp field of the BWAVs precisely matching the time-code of the corresponding footage.
When you start editing your film, one of the first things you will do is to import all your footage and sound recordings and here is our first big potential problem because, when you import the sound files, your editing software will likely overwrite or delete much of the metadata. The first thing you should do before you import anything is to make a copy of your production sound recordings and work from the copies. This guarantees you have a copy of all the files with all the original metadata. Once you start editing, make sure you don't change any of the audio file names. When you've finished editing you will need to export your sequence for the audio post professionals, this is where things can get tricky!
On the plus side, virtually all audio post professionals use AVID's ProTools software, on the minus side, there are a few different ways of exporting your sequence and getting it wrong could cost you dearly. The two most common export container formats are OMF (pronounced "oom-fy") and Advanced Authoring Format (AAF). AAF is the most recent and slightly preferred of the two containers. AVID systems can export AAF natively whereas FCP or FCPX requires an addon like "Automatic Duck". Other less common editing programs may provide AAF export functionality but they often don't strictly adhere to the AAF specifications and result in ProTools not being able to open the AAF. The general workflow is to:
1. Export the video separately, adding Burnt In Time-code (BITC), using the video codec/resolution requested by the audio post team and including your sound mix in the video as a guide.
2. Export an audio only AAF (delete the video tracks if necessary), linking to the audio files, rather than embedding.
3. Send the video, the AAF and ALL the original production sound recordings to the audio post team.
Exactly how you achieve the video and AAF export will depend on your editing software and would normally be handled by the Asst. Picture Editor. If you haven't done this before, expect the odd problem and to have to do some research in order to produce an AAF which ProTools will open. But watch out for a few obvious problems: 1. Start your time-code at 01:00:00:00 and if you're working in reels, start each reel on the hour (EG: Reel 3 would start at 03:00:00:00). 2. Don't mix frame rates in your sequence. 3. Some NLE's allow mono, stereo or multi-track material on the same audio track. Don't do this though, make sure each audio track only contains audio clips of the same channel count. 4 Include a 2 pop, 1 frame of 1Khz tone at -20dBFS exactly 2 seconds before the first frame of action (FFOA) ie. 48 frames before the FFOA, if your frame rate is 24fps and add a corresponding (1 frame) of white screen to the picture at the same location. If you're working in reels, you need to do this for each reel and add a tail pop 2 seconds after the last frame of action (LFOA) for every reel except the last.
What should happen is all your audio tracks and edits are imported from the AAF and linked to the original audio recordings. If you have embedded (rendered) the audio in the AAF this can cause problems because if the audio team need to change an edit or look for room tone or additional material outside your edit boundaries we can only do this up to the limit of the handles you have set when rendering the AAF (usually 2 secs). A referenced (linked) AAF on the other hand allows us to change your edit boundaries up to the limits of the entire original audio recording.
Now let's take an extremely common situation: We're editing dialogue and come across a problem which can't be adequately fixed with processing. The solution is to find alternate, replacement dialogue by going through the audio files to locate all the alternate takes, wild tracks and different mic recordings (lav, boom, etc) and importing and synchronising them. Baring in mind a feature film usually generates thousands of production sound files, this task can easily turn dialogue editing into a nightmare, taking weeks or even months to sort out (and costing a fortune). If there isn't time to go through all the files looking for alternate dialogue, problems will have to be solved with ADR, which lowers the performance quality and again costs a fortune! However, here is where our metadata can save the day, providing of course all the relevant metadata was correctly entered by the production sound mixer and that metadata has been preserved by linking the AAF to the original audio files (rather than embedding). A couple of mouse clicks on the offending dialogue and ProTools will examine it's metadata and compare it with the metadata of all the production sound files and in seconds present a list of all the alternate takes and mic recordings. An additional second is all it takes for one or all of those alternates to be automatically imported, edited and synchronised. A task taking potentially an hour or longer maybe reduced to just a few seconds, multiply this situation a hundred or more times in an average feature and you can see why accurate metadata is so important!
Feel free to ask any questions all this info might raise.
G
Firstly, it's worth understanding a little about audio files: The best choice for all concerned, the production sound mixer, picture editor and audio post team is the Broadcast Wav format (.wav), although MXF format is OK too. The broadcast Wav Format (BWF) was specifically designed for use in broadcast and film applications. The BWF has two storage areas, one for the digital audio data ("essence") and the other for numerical and text data ("metadata"). The most obvious use of metadata is to store the audio file name but there are many other fields of information stored in the metadata which, if used properly, can massively aid the audio post workflow. Some of the metadata fields are written automatically when recording, depnding on the recorder settings, for example; the sample rate, bit depth, file creation date, frame rate, duration, etc. Other fields need to be entered manually, for example; File name, Project, Sound Roll, Scene and take numbers, Circled, etc. This information should be added by the production sound mixer during recording. The Time Stamp fields are also incredibly useful! Ideally, the camera/s and the sound recorder are being fed time-code from a single common source. This will result in the original time stamp field of the BWAVs precisely matching the time-code of the corresponding footage.
When you start editing your film, one of the first things you will do is to import all your footage and sound recordings and here is our first big potential problem because, when you import the sound files, your editing software will likely overwrite or delete much of the metadata. The first thing you should do before you import anything is to make a copy of your production sound recordings and work from the copies. This guarantees you have a copy of all the files with all the original metadata. Once you start editing, make sure you don't change any of the audio file names. When you've finished editing you will need to export your sequence for the audio post professionals, this is where things can get tricky!
On the plus side, virtually all audio post professionals use AVID's ProTools software, on the minus side, there are a few different ways of exporting your sequence and getting it wrong could cost you dearly. The two most common export container formats are OMF (pronounced "oom-fy") and Advanced Authoring Format (AAF). AAF is the most recent and slightly preferred of the two containers. AVID systems can export AAF natively whereas FCP or FCPX requires an addon like "Automatic Duck". Other less common editing programs may provide AAF export functionality but they often don't strictly adhere to the AAF specifications and result in ProTools not being able to open the AAF. The general workflow is to:
1. Export the video separately, adding Burnt In Time-code (BITC), using the video codec/resolution requested by the audio post team and including your sound mix in the video as a guide.
2. Export an audio only AAF (delete the video tracks if necessary), linking to the audio files, rather than embedding.
3. Send the video, the AAF and ALL the original production sound recordings to the audio post team.
Exactly how you achieve the video and AAF export will depend on your editing software and would normally be handled by the Asst. Picture Editor. If you haven't done this before, expect the odd problem and to have to do some research in order to produce an AAF which ProTools will open. But watch out for a few obvious problems: 1. Start your time-code at 01:00:00:00 and if you're working in reels, start each reel on the hour (EG: Reel 3 would start at 03:00:00:00). 2. Don't mix frame rates in your sequence. 3. Some NLE's allow mono, stereo or multi-track material on the same audio track. Don't do this though, make sure each audio track only contains audio clips of the same channel count. 4 Include a 2 pop, 1 frame of 1Khz tone at -20dBFS exactly 2 seconds before the first frame of action (FFOA) ie. 48 frames before the FFOA, if your frame rate is 24fps and add a corresponding (1 frame) of white screen to the picture at the same location. If you're working in reels, you need to do this for each reel and add a tail pop 2 seconds after the last frame of action (LFOA) for every reel except the last.
What should happen is all your audio tracks and edits are imported from the AAF and linked to the original audio recordings. If you have embedded (rendered) the audio in the AAF this can cause problems because if the audio team need to change an edit or look for room tone or additional material outside your edit boundaries we can only do this up to the limit of the handles you have set when rendering the AAF (usually 2 secs). A referenced (linked) AAF on the other hand allows us to change your edit boundaries up to the limits of the entire original audio recording.
Now let's take an extremely common situation: We're editing dialogue and come across a problem which can't be adequately fixed with processing. The solution is to find alternate, replacement dialogue by going through the audio files to locate all the alternate takes, wild tracks and different mic recordings (lav, boom, etc) and importing and synchronising them. Baring in mind a feature film usually generates thousands of production sound files, this task can easily turn dialogue editing into a nightmare, taking weeks or even months to sort out (and costing a fortune). If there isn't time to go through all the files looking for alternate dialogue, problems will have to be solved with ADR, which lowers the performance quality and again costs a fortune! However, here is where our metadata can save the day, providing of course all the relevant metadata was correctly entered by the production sound mixer and that metadata has been preserved by linking the AAF to the original audio files (rather than embedding). A couple of mouse clicks on the offending dialogue and ProTools will examine it's metadata and compare it with the metadata of all the production sound files and in seconds present a list of all the alternate takes and mic recordings. An additional second is all it takes for one or all of those alternates to be automatically imported, edited and synchronised. A task taking potentially an hour or longer maybe reduced to just a few seconds, multiply this situation a hundred or more times in an average feature and you can see why accurate metadata is so important!
Feel free to ask any questions all this info might raise.
G