How to compress DSLR videos to a manageable size
A lot has been written and spoken about the movie making capabilities of the current generation of digital SLR cameras that were originally designed for still photography. Though the capability has existed for a long time now, it was in the commercial interests of camera makers to “segment” the market into customers who wanted to shoot still images and customer’s who wanted to shoot video. These manufacturers have now been forced to merge their market segments thanks largely due to the growing base of customers who do want both in the same device. There is in fact a growing aversion among enthusiast customers to buy a a camcorder largely due to two reasons: One is the availability of decent video capabilities on higher end smartphones (which cost the same as a good camcorder anyway). Second is the realization that the it is not convenient to lug around a bundle of special purpose devices and switch between them when a single device that can do the same job albeit with lesser features is available in the market. If you are in the market looking for a device that can do ‘prosumer’ grade photography while also allowing you to take high quality video, you should consider the new (now old) kid on the block – Mirror-less or micro four thirds cameras. The naming is reflective of the disdain camera manufactures have had for the uneducated customer! Neither the term mirror-less nor the term micro four thirds makes any sense unless you know the internal construction of a camera. Naming aside, what’s important to know is that all camera manufactures have one or more models in this category. It is also interesting that Canon is literally a non player in the category considering the lukewarm response to their EOS-M cameras.
After having read tons of online ‘literature’ and talking to a couple of my friends who are professional photographers, I ended up buying a Canon EOS 700D DSLR camera along with a poor man’s kit of a 50mm prime lens and an external flash. The flash alone cost me more than the point and shoot camera that I had owned and loved for the previous 7 years. The jump in quality from my Canon point and shoot (powershot A630) was significant considering that I had taken the following pictures using my point and shoot camera in 2007:
The improvement in quality was far more significant for videos. While the point and shoot had video capabilities, I had stopped using it after an initial trial because the quality and size of the video was very poor. The DSLR on the other hand can record high definition video at 1080p. Experience with the DSLR taught me the one great advantage and three drawbacks with DSLR video:
The BIG advantage:
Even an entry level DSLR can beat the socks out or a “prosumer” camcorder for videos shot in low light conditions. Given how cameras treat light, you can be reasonably assured to be in low light conditions unless you are shooting outdoors. My primary purpose was to shoot videos of my baby indoors. The quality of footage can be controlled by a dizzying array of interchangeable lenses. This is something you cannot do with a camcorder. This advantage alone dwarfs the disadvantages below.
The three disadvantages:
- The size of video files are abnormally large. A 30 second clip is around 170 MB (mega bytes) in size! This translates to a regular 90 minute movie size being 15 GB!
- It is difficult to keep a moving subject in continuous focus. This is getting fixed in the newer models.
- You have limit your recordings to short clips of around 12 minutes each. The heat buildup on the sensor on the cameras is the reason for this limitation.
Of the 3 limitations above, it is possible to address the huge file size issue once you have transferred your videos to your computer. This is not such an attractive option for people who would like to upload their videos directly to media sharing websites such as YouTube. After trying out many options (including Adobe Premierie, VirtualDub etc), I have concluded on the following workflow. This workflow is ideally suited if you are not planning to make a lot of edits to your video. My aim is to achieve two things:
- Shrink the size of the video while maintaining as much of the quality as possible. My rule of thumb – if I cannot make out the difference in quality in the compressed video, it is OK. People don’t mind minor reduction in video resolution if the content is interesting. This is one of the reasons why Youtube is more popular than Vimeo though Vimeo allows higher resolution uploads(edit: YouTube has added support for high resolution videos now). There is no fun is waiting for a high resolution video to stream into your box.
- Merge clips without having to lose quality just because of the merge (I don’t want to re-render just for the sake of merging).
I was pleasantly surprised to discover that I can do both of the above with the tiniest bit of software possible for such a task. This is my workflow for compressing DSLR videos:
- Download MPEG StreamClip from http://www.squared5.com/.This is a 800 KB file that can be run as-is. No installation is required.
- Download and install Quick Time alternative version 1.81. This is required only if you do not have Apple Quick time installed on your system. You can download quick time alternative from http://filehippo.com/download_quicktime_alternative/2615. The installer is a 13 MB download.
Using MPEG StremClip:
- The MPEG Stream clip interface is simple though they could have had two versions of of the UI – one with with the mumbo jumbo known only to video editing professionals and one for the rest of the planet. As it stands, you need to understand a few terms to get the tool to do what you want.
- Open the clip that you want to compress using the Open Files option on the file menu. Once the file is opened, navigate to the “Export to MPEG-4” option on the file menu. This will open up the following dialog window:
- If you are planning to transfer the final output to any Apple device, click on the iTunes button, choose the device and you are done! Simply click the Make MP4 button and your compressed video is ready. If you want to control the settings, proceed to step 5.
- Compression technique : You have three options for the compression technique. I prefer the H.264 compressor. H.264 is a compression standard that is incredibly popular and is hence guaranteed to work on the largest number of devices. If you don’t know what H.264 is don’t bother. Just use it!
- Compression Quality : This is the slider below the compression technique selection box. The default is 50%. Change it to 100%. We are compressing anyway. Lets do a good job of that!
- Limit Data Rate : This is the only option you need to understand if your main aim is reduction in file size. This option is essentially asking you how much space should one second of video consume in your output. Video compression is not linear (all seconds are not the same!) and hence it is a average value. The tool has a neat feature of providing an estimate of the compressed file based on the data rate you choose. My choice is based on the size of regular DVD movie discs. I would like to compress 90 minutes of video into about 2 GB. This translates to a bit rate of 0.3 MBps (note the upper case B). You can see in the screen grab above that this translates to about 10 MB for a 30 second clip.
- Sound : Choose MPEG-4, stereo 128 Kbps. You can safely drop the bit rate of the audio without fear of losing quality though the gains would not be significant. Remember most internet radio stations broadcast at 128 KBps or lesser. I listen to a radio station regularly that broadcasts at 28 Kbps!
- Frame Size : I leave this option as-is. The tool detects the frame size of the input file and selects that by default. Frame size is the physical dimension (in pixels) of the output video.
- The other options: All other options are best left untouched. You need to change the frame rate only if you want to convert a 60/120 fps clip to render at 30 fps to give the slow motion effect. Frame blending should not be needed unless you change the frame rate. De-Interlace video should not be needed for DSLR videos. I have tried mutl-pass rendering and I could not really observe a big difference for the clips I tried it on.
- That’t it! Go ahead and press the Make MP4 button and wait for the video to render. This can take a while depending on the size of your video. A 30 second clip takes a couple of minutes t render on an old Intel Centrino based system. Video rendering speeds are dependent on the processing power you have.
- Compare the output video with the original. If you are happy with the quality of the output, you can save the setting as a preset. Launch the export dialog again, choose the same settings and press the presets button to save your settings as a preset. You don’t have to do this every time once you have a preset.
- If you want to combine multiple clips, open all of them (notice the option is labelled Open Files and not open file) and follow the same steps as above.
Do let me know via comments if this works for you. MPEG StreamClip is one of the most under-rated tools for simple video editing tasks – much like how Microsoft treated OneNote for the first few years after its launch.