DVD as a format for live video playback - an analysis.
As more and more computer based video editing
systems gain the ability to burn video to DVD, I can see this becoming the most
common format for the delivery of 'home-made' playback video for live
events.
This has some good consequences and some unexpected side-effects. Read on for how to get the best of the DVD format at a VLOBLIVE event.
This has some good consequences and some unexpected side-effects. Read on for how to get the best of the DVD format at a VLOBLIVE event.
DVD playback of pre-recorded video inserts for
live events. Got to be a good thing right? I mean, it's easy to make them, they
are interactive, high quality, etc. etc. etc. What's not to
like?
Well let's consider the pros and cons of this format:
Good things:
- now cheap to 'author' and blank media inexpensive
- Potential for higher quality video and audio
- more convenient physical format (easier to carry/post etc.)
- easier cueing of multiple items on same disc
- menu system
- support for multi-channel audio
- possible to pause and get good still image
- possible to loop endlessly between A-B points and not wear anything out
Bad things:
- confusion about format compatibility between writers (plus vs dash etc.)
- codecs sensitive to 'out of spec' video
- video quality can be seriously compromised by over-zealous compression
- it's REALLY easy to burn a disc in the wrong video format (PAL or NTSC)
- careless handling can render discs unreadable (especially recordable ones)
- variable delay after hitting 'play' makes cue-ing a bit random
- menu can get in the way of fast back to back playouts
- consumer features (like OSD) can get in the way
As you can see most of the bad things are more to do with how the format is used, rather than inherent limitations, and can easily be worked around with some effort. Here are my suggestions, based mostly on personal experience, of how to get the best from recordable DVD as a playback format.
Preparation tips:
- burn to -RW or +RW first as 'tester' disc.
This isn't a specific live tip, but it's still a good idea. To avoid making lots of coasters, I suggest always doing your FIRST burn to a DVD-RW or DVD+RW disc. This way, if you miss something, or it doesn't work as you expected, then you can erase and re-burn till you get it right. I do, however, recommend doing the 'master' burn to a -R or +R disk, as they have better player compatibility and are more robust.
- use minimum compression possible
Most clips will be MUCH shorter than the capacity of the DVD, so you want to use the best possible quality setting in whatever encoding software you are using.
Minimum compression = fastest allowable datarate = best quality video.
In iDVD on a mac the settings are a bit confusing, but you want 'best quality' not 'best performance' in the encoder settings section of the preferences, which means turning off background rendering.
(the reason is that with background rendering iDVD doesn't know exactly how much video you have still to put on the disc, so is conservative about compression settings. If you wait to encode until you have everything in place, it can do a better job at chosing a compression setting that best fits your video duration)
If you have a more sophisticated DVD authoring tool like DVD Studio Pro from Apple you can really tweak the compression settings, but be careful as there IS a maximum data-rate beyond which most DVD players will choke at decompressing the MPEG2 video. Apple recommend a maximum of 8Mbps to ensure playback without dropping frames on all DVD players.
- make useful menus
A DVD for live playback is no place for fancy animated menus. The key here is information and ease of navigation. Use the menu to clearly identify the disc, the clips and any relevant info to each clip (length, in and out details, audio details etc.) Make it REALLY quick to know which clip is which and to select it.
Also make the menu background unobtrusive, so just in case you ever drop out to the menu when live, you don't get laughed at too much.
- add countdowns
To cope with the variable time from pressing 'select' on a menu and getting video, I suggest that you add a short (3 sec) countdown to black immediately before the start of each clip so you know EXACTLY when to press pause (on the black bit!) to cue the clip. This may sound like a backward step, but remember you have to fade up your video mixer on this clip, so this way you can fade up on pause, press play and never miss the first second of the clip.
You can find an example countdown here
- add trailing black
You REALLY want to do this so that if you are a bit slow fading out at the end of the clip you don't jump back to the menu while still live on screen. Yes I've done that. It's not nice.
- add fade ins and fade outs to audio and video
You always get a more elegant start and end by adding even a very short (0.5 sec) fade in or fade out to the video. You will also get thanked by your audio engineer if you fade in any audio that is coming in halfway through (i.e doesn't have a clean start)
- use broadcast safe filter
If your NLE software allows it (like Final Cut Pro) then apply a broadcast safe filter across all the video clips. This ensures that luminance and chrominance (brightness and colour) are kept within legal values and so don't upset the compression to MPEG2. This is especially relevant for clips filmed on comsumer DV cameras that tend to over-egg the colour considerably.
I have seen problems with iMovie and iDVD in the past with very colourful parts of a scene turning purple as the values are clipped.
- consider making 'nose to tail' video segments
the ideal DVD for live work would be one that worked like a pro CD player. It played a track then went into pause, waiting for you to press play for the next track, then pause again etc.
You could make a special script on DVDSP to daisy-chain all the clips so that they play one after the other with just a 'holding' page in between. I've still to try this (just got DVDSP) but it looks very useful.
Usage tips:
- look after discs
DVD-Rs are quite susceptible to scratches and dust - much more so than normal CDs or even commercial DVDs.
Buy a brand name blank media (not no-name cheap rubbish) and look after them and keep them in their cases when not in use. Consider having a 'place' where DVDs are kept during a live show. Put them down on their backs (sensitive side up) to avoid scratching the surface. If you have to wipe dust off use a lens brush or spectacle cloth and NEVER wipe round in circles - always straight lines radially. In theory the error correction can cope with momentary blips but not long drop-outs caused by scratches that track around the disc.
- make a backup and ask for backups
Always burn a spare DVD. Keep it in a different place, and don't use it unless you have to.
This may sound paranoid, but I've had several DVD-Rs just decide not to work during a live gig, and especially if others are not so careful about choice of blank media etc.
- buy a suitable player
See my suggestions here for features to look for to make your life easier for live event playback.
Well let's consider the pros and cons of this format:
Good things:
- now cheap to 'author' and blank media inexpensive
- Potential for higher quality video and audio
- more convenient physical format (easier to carry/post etc.)
- easier cueing of multiple items on same disc
- menu system
- support for multi-channel audio
- possible to pause and get good still image
- possible to loop endlessly between A-B points and not wear anything out
Bad things:
- confusion about format compatibility between writers (plus vs dash etc.)
- codecs sensitive to 'out of spec' video
- video quality can be seriously compromised by over-zealous compression
- it's REALLY easy to burn a disc in the wrong video format (PAL or NTSC)
- careless handling can render discs unreadable (especially recordable ones)
- variable delay after hitting 'play' makes cue-ing a bit random
- menu can get in the way of fast back to back playouts
- consumer features (like OSD) can get in the way
As you can see most of the bad things are more to do with how the format is used, rather than inherent limitations, and can easily be worked around with some effort. Here are my suggestions, based mostly on personal experience, of how to get the best from recordable DVD as a playback format.
Preparation tips:
- burn to -RW or +RW first as 'tester' disc.
This isn't a specific live tip, but it's still a good idea. To avoid making lots of coasters, I suggest always doing your FIRST burn to a DVD-RW or DVD+RW disc. This way, if you miss something, or it doesn't work as you expected, then you can erase and re-burn till you get it right. I do, however, recommend doing the 'master' burn to a -R or +R disk, as they have better player compatibility and are more robust.
- use minimum compression possible
Most clips will be MUCH shorter than the capacity of the DVD, so you want to use the best possible quality setting in whatever encoding software you are using.
Minimum compression = fastest allowable datarate = best quality video.
In iDVD on a mac the settings are a bit confusing, but you want 'best quality' not 'best performance' in the encoder settings section of the preferences, which means turning off background rendering.
(the reason is that with background rendering iDVD doesn't know exactly how much video you have still to put on the disc, so is conservative about compression settings. If you wait to encode until you have everything in place, it can do a better job at chosing a compression setting that best fits your video duration)
If you have a more sophisticated DVD authoring tool like DVD Studio Pro from Apple you can really tweak the compression settings, but be careful as there IS a maximum data-rate beyond which most DVD players will choke at decompressing the MPEG2 video. Apple recommend a maximum of 8Mbps to ensure playback without dropping frames on all DVD players.
- make useful menus
A DVD for live playback is no place for fancy animated menus. The key here is information and ease of navigation. Use the menu to clearly identify the disc, the clips and any relevant info to each clip (length, in and out details, audio details etc.) Make it REALLY quick to know which clip is which and to select it.
Also make the menu background unobtrusive, so just in case you ever drop out to the menu when live, you don't get laughed at too much.
- add countdowns
To cope with the variable time from pressing 'select' on a menu and getting video, I suggest that you add a short (3 sec) countdown to black immediately before the start of each clip so you know EXACTLY when to press pause (on the black bit!) to cue the clip. This may sound like a backward step, but remember you have to fade up your video mixer on this clip, so this way you can fade up on pause, press play and never miss the first second of the clip.
You can find an example countdown here
- add trailing black
You REALLY want to do this so that if you are a bit slow fading out at the end of the clip you don't jump back to the menu while still live on screen. Yes I've done that. It's not nice.
- add fade ins and fade outs to audio and video
You always get a more elegant start and end by adding even a very short (0.5 sec) fade in or fade out to the video. You will also get thanked by your audio engineer if you fade in any audio that is coming in halfway through (i.e doesn't have a clean start)
- use broadcast safe filter
If your NLE software allows it (like Final Cut Pro) then apply a broadcast safe filter across all the video clips. This ensures that luminance and chrominance (brightness and colour) are kept within legal values and so don't upset the compression to MPEG2. This is especially relevant for clips filmed on comsumer DV cameras that tend to over-egg the colour considerably.
I have seen problems with iMovie and iDVD in the past with very colourful parts of a scene turning purple as the values are clipped.
- consider making 'nose to tail' video segments
the ideal DVD for live work would be one that worked like a pro CD player. It played a track then went into pause, waiting for you to press play for the next track, then pause again etc.
You could make a special script on DVDSP to daisy-chain all the clips so that they play one after the other with just a 'holding' page in between. I've still to try this (just got DVDSP) but it looks very useful.
Usage tips:
- look after discs
DVD-Rs are quite susceptible to scratches and dust - much more so than normal CDs or even commercial DVDs.
Buy a brand name blank media (not no-name cheap rubbish) and look after them and keep them in their cases when not in use. Consider having a 'place' where DVDs are kept during a live show. Put them down on their backs (sensitive side up) to avoid scratching the surface. If you have to wipe dust off use a lens brush or spectacle cloth and NEVER wipe round in circles - always straight lines radially. In theory the error correction can cope with momentary blips but not long drop-outs caused by scratches that track around the disc.
- make a backup and ask for backups
Always burn a spare DVD. Keep it in a different place, and don't use it unless you have to.
This may sound paranoid, but I've had several DVD-Rs just decide not to work during a live gig, and especially if others are not so careful about choice of blank media etc.
- buy a suitable player
See my suggestions here for features to look for to make your life easier for live event playback.
Posted: Wed - June 29, 2005 at 08:03 AM |
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This site contains my personal views, ideas, tips, tricks and rants about doing live video, IMAG or graphics at live events on a very low budget. They are published as I get time, in a style closely approximating a weblog. Dave C.
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My name is Dave Chalmers and I live in Edinburgh in Scotland, UK. My background is in Electronics, but for 10 years I have been helping to put on live video at events in central Scotland in my spare time. Through the course of these events, nearly all on very constrained budgets, I have learned a few things about what works and what doesn't. While I would not claim to be able to give you all the answers, I can at least help you avoid some of the mistakes.
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Published On: Jul 06, 2006 11:37 PM
Total entries in this category: 12
Published On: Jul 06, 2006 11:37 PM