Encoding for Online Distribution 101

Helpful and informative independent filmmaker sources

Encoding

Encoding is the format your movie is recorded, or stored, or converted to. It is a digital format used for displaying the movie. Everything on the Web is or has migrated to H.264 (an MPEG group version) as the encoding of choice for video (movies). Flash and other codecs are still around, and still supported on the Web, and Netflix is still using a proprietary form of Microsoft's VC-1 (Microsoft's old video player format). VC-1 is quite good, but not as good as H.264.

H.264 is created by the MPEG video group that created MPEG-2, which has been a digital standard for many decades. H.264 has much better compression than MPEG-2. It retains most of the original color information (4.2.2). It is backed by major manufacturers and supported in almost every browser.

Color information is also affected by how many bits the encoder outputs. Cameras with an 8-bit output are only able to store 256 colors, which is a very low color depth. You can store a larger variety of colors by increasing the number of bits used to store the colors. For example 64-bit computers are able to store and display 16 million colors. But that comes at a price. It takes a lot more bandwidth to send, and a lot more computing power to display. 12-bit cameras store over 14,000 colors, and 14-bit cameras store over 16,000 colors. It is very difficult to do color correction using only 8 bits.

H.264 isn't the end of story. H.265 encodes to around half the size of H.264, but requires very intensive decoding, which many devices may not support because they don't have a powerful enough CPU and RAM. Several manufacturers of encoders continued to work on H.264 with various proprietary enhancements. As a group, they brought those enhancements together into MPEG Dash. MPEG Dash is likely to be the next important encoder for production.

If it's video and goes online, it's best to have it in H.264 format, or MPEG Dash. Why? Because bandwidth costs money. A two hour movie in H.264 format, 30 fps, 1080p, runs around 16 Gigabyte in size. To stream that from the least expensive CDN servers is likely to cost around $4.00, and this size file will not stream to a lot of computers with low bandwidth.

Encoding affects the appearance of your movie. Encoders use compression to create the smallest possible file size, so it takes less bandwidth, whether over the air, cable, DVD, or the Internet. If you sent in MPEG-2 format with low compression, the file would be too large to send for some viewers. So compression is essential. But most compression formats are "lossy," meaning that they remove "unnecessary" picture and audio information. However, removing too much information causes a variety of problems. They are also "predictive," meaning that they expect the next frame to appear the same, and only send the information that changed.

Too highly compressed images appear blocky, splotchy, or lack detail. Blocky means that you see visible squares on the screen. You lose the impact of detail in the image. Due to prediction, you might also see parts of people's faces standing still as their faces move. In movies with fast action, or even movies with some close up action, you might see choppy movement.

The number of frames per second is also set on the camera and then the editing encoder. Low frame rates emphasize choppiness. Low action movies can be in the industry standard 24fps for NTSC (American) movies, or 25fps for PAL European movies. High action movies and sports should be in the industry standard 30fps for both NTSC and PAL. Frame rates above 30fps currently take too much Internet bandwidth. Delivery in greater than 30fps makes very little difference, unless it is sports where a lot of detail is wanted.

Note that NTSC encode frame rates are actually 1% lower than 24 or 30, while PAL frame rate is 25 fps.

Encoding is an art. Following are some things to consider on the video portion.

The masters of film have never emphasized detail on the large screen. Today's 1080p television broadcasts show far more detail than film ever did. Why were details not emphasized? Because the world of film is a fictitious environment and too much detail destroys the fictional dream. They used "pancake" makeup that hid every blemish on an actor's face. Background detail was beautiful, but rarely crisp. This was a function of the type of film used, and camera techniques that emphasize "Bokeh," showing background detail out of focus.

While it is often nice to see vivid detail in some images, it is also good not to see detail overly clearly. What experts have found is that 720p is often the best HD format for sending. If the viewers system upscales it to 1080p, it has a better appearance than the same movie sent in 1080p. Additionally, a movie that is encoded in 720p, and then given a second encoding pass in 720p, often looks better and is more compressed than the first pass.

Note that at this date, television broadcast in the US is typically 720p or 1080i, including programs on satellite and cable carriers, which requires half the bandwidth of 1080p. Blue Ray discs and online movies are in 1080p. Newer digital televisions generally can display 1080p. Televisions are not expected to have 4K resolution (4x 1080p) for at least another 5 years due to lack of demand, slow technology development, very high price, and lack of 4K content. Forget 4K TVs for five years.

For video encoding, during editing or additional compression, you should be looking at the encoded output on a large screen 1080p monitor, or close up on a 21 inch monitor, to see how it looks. Calibrating your monitor is important. Analog monitors lose brightness over the years, and LED monitors lose about 30% of their brightness in the first year. Calibrate your color and brightness levels before you start work, or you may have no idea how your movie actually looks. For LED and LCD monitors, you can use The Lagom LCD monitor test pages for calibration.

Important: Always store a copy of the original, not just the encoded version. Even the H.264 version from a digital camera should be stored as is, as the original. Edited copies never have as much of the original picture and sound information.

Next page: Encoding for smooth streaming and multiple devices.

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Encoding for smooth streaming and multiple devices

Internet traffic often runs into bottlenecks that limit bandwidth. This is especially true for the "last mile," meaning the ISP service and overloading. Past studies showed that people usually got exactly half the bandwidth that they sign up for, but the FCC has been pushing ISPs to get closer to what they advertise and they are around 80% there. What happens to movies when bandwidth suddenly drops? It simply stops showing until it can receive enough bits. You see the "Rebuffering" message. Thankfully that problem has been addressed on some servers. With "smooth streaming," the server automatically senses the drop in bandwidth and selects a lower bandwidth version of the movie.

People generally don't notice small drops in bandwidth when smooth streaming is in use. Bandwidth can drop from 4Mbps to 380K, and the movie will still display. But with that much drop, people will notice the change in resolution (detail level of the picture).

To make this magic happen, the movie has to be encoded in 4 to 6 different versions with less bitrates. So the movie will have to be encoded in 4 to 6 versions for NTSC format. For worldwide distribution, it will also need 4 to 6 versions in PAL format. Some newer server software can automatically select the correct bitrate and send from just one version.

Multiple bitrate versions are also necessary to send to various devices. Many devices, such as cell phones with Internet capabilities, have small screens with resolution less than 1080p. These many versions are also needed for sending the movie to lower bandwidth devices.

When multiple bitrate versions are used, the "keyframes" on the versions must be synched. Synch means they must have the same keyframe. Keyframes from 2 to 5 seconds works well for this. Two is recommended.

Next: Encoding Sound

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Encoding Sound

Sound is the most important element of a movie. While excellent visual quality and visual portrayals of dramatic action are what people go to movies to see, most of the information is delivered to the audience in the form of sound.

Around 80% of the effectivness of the delivery of words comes from the non-verbal cues - the actors expressing the emotional content through body language, verbal expressiveness, and actions.

The H.264 encoder uses Dolby Digital AC-3 sound. It preserves wonderful sound for theaters and home theater viewing. Problem: Wonderful sound output for a theater is not great for home viewing. Many people have 10 to 30 watt speakers on their televisions, and less on their computers. They may get great video detail, but not sound. Theaters blast sound at a very high level, so every sound is audible. People in front of a TV have lesser quality systems and often don't hear sound details.

This has very practical implications for editing and encoding for digital distribution over the Internet. Most devices will not have great sound systems. So much of the sound may be unintelligible. This is for a variety of reasons.

The human ear passes information to the brain at a wide range of volume levels. It actually takes twice the power (3db change) for the human ear to notice a difference. So we hear at different volume levels, crickets chirping in the woods outside the window, a frog adding to the serenade, the clock ticking on the wall, the radio playing, and the child screaming in our ear. We hear these just fine and are able to differentiate between them. We know that the frog is not a cricket on the radio.

The ear changes as people age. As people age, they lose the ability to hear higher frequencies. People in their sixties, or those who have listened to a lot of loud music or machine noise, often lose the ability to differentiate a speaking voice from the background sound, which means they can't understand what people say. This makes the inherent problems of sound (below) even worse. Over the next twenty years, each age in our population will be equally represented. There will be as many twenty-year olds as there are 80 year olds. People who can't understand what actors are saying simply won't watch. The current trend of actors speaking in husky voices or hushed tones should be abandoned. The TV audience may have no idea what they are saying.

When TV sound competes for our ear's attention, we miss a lot of detail. For example, morning news programs often have music or crowd noise in the background as the hosts speak. You really can't decipher what the host is saying because the engineers have the music level too high, or microphones unshielded from crowd noise, and it drowns out the speaker.

Following are some recording and editing practices, for Internet distribution, that will serve you well, even for film and TV:

  • Loud music, when there is no voice, is not a problem.
  • Voice level should be recorded at -12db (especially if not using clipping). -12db allows for normal fluctuations so that volume doesn't rise above 0db. In editing, hold the volume level below 0db.
  • Music and background noise should be recorded at -6 to -12db below voice, (meaning at -18 to -24db) so that voice is always intelligible above background and music. When there is no voice competing for attention, music volume can rise to -12db.
  • Constant level devices should be avoided. They will usually make background noise flood the audio when there is no voice.
  • Voice and other sounds should never be recorded above 0db. It causes distortion in analog, or sound that is too loud in digital plus distortion.
  • When characters speak in low voices, or in whispers, the boom mike should be held much closer, or editing should boost the voice to -12db so that the audience can actually hear what they are saying.
  • - Dorian

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Reference

Companies mentioned, or commonly mentioned on this Web site:

Amazon.com® is a Registered Trademark of Amazon.com, Inc.
AOL® is a Registered Trademark of AOL Inc.
BOXEE® is a Registered Word Mark of Boxee Inc.
BLOCKBUSTER® is Registered Trademark of Blockbuster L.L.C.
iTunes® is a Registered Trademark of Apple®
CINEMANOW™ is a trademark of BBY Solutions, Inc.
Comcast® is a Registered Trademark of Comcast Corporation
Disney is a business name of Disney Enterprises, Inc.
Fandango℠ is a proprietary service mark of Fandango, Inc.
FIos® is a Registered Trademark of Verizon Trademark Service
HBO® is Registered Trademark of Home Box Office, Inc.
HULU® is Registered Trademark of HULU®, LLC.
Moviefone® and Moviefone.com® are Registered Service Marks of AOL Inc.
MOVIES.COM® is a Registered Trademark of Fandango, Inc.
MOVIEWEB® is a Registered Service Mark of MovieWeb, Inc.
NETFLIX® is a Registered Trademark of NETFLIX®, INC.
REDBOX® is a Registered Trademark of Redbox Automated Retail, LLC
ROKU® is a Registered Word Mark of Roku, Inc.
Sony® is a Registered Word Mark of Sony Corporation
Sundance Institute is not trademarked, but is used since 1981 by Sundance Institute, which hosts the Sundance Film Festival
Sundance Channel® is a Registered trademark of Sundance Enterprises, Inc.
TiVo® is a Registered trademarks of TiVo Inc.
VUDU™ is a trademark of VUDU, Inc.
XBOX® is Registered Trademark of Microsoft Corporation.
YouTube® is a Registered Trademark and Service Mark of Google, Inc.
Any trademark not listed out of oversight is a Trademark or Registered Trademark of it's respective owner.

Mention of any business in this article is not intended to endorse, disparage, or favor any business.

Movie names that are mentioned are not given reference citations. This is because numerous studios are involved in production, and they then assign distribution rights to multiple distributors, and these rights can be sold to other distributors. For production and distribution information on any movie mentioned, consult the Internet Movie Database, or other authoritative listing.

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Reference

Companies mentioned, or commonly mentioned on this Web site:

Amazon.com® is a Registered Trademark of Amazon.com, Inc.
AOL® is a Registered Trademark of AOL Inc.
BOXEE® is a Registered Word Mark of Boxee Inc.
BLOCKBUSTER® is Registered Trademark of Blockbuster L.L.C.
iTunes® is a Registered Trademark of Apple®
CINEMANOW™ is a trademark of BBY Solutions, Inc.
Comcast® is a Registered Trademark of Comcast Corporation
Disney is a business name of Disney Enterprises, Inc.
Fandango℠ is a proprietary service mark of Fandango, Inc.
FIos® is a Registered Trademark of Verizon Trademark Service
HBO® is Registered Trademark of Home Box Office, Inc.
HULU® is Registered Trademark of HULU®, LLC.
Moviefone® and Moviefone.com® are Registered Service Marks of AOL Inc.
MOVIES.COM® is a Registered Trademark of Fandango, Inc.
MOVIEWEB® is a Registered Service Mark of MovieWeb, Inc.
NETFLIX® is a Registered Trademark of NETFLIX®, INC.
REDBOX® is a Registered Trademark of Redbox Automated Retail, LLC
ROKU® is a Registered Word Mark of Roku, Inc.
Sony® is a Registered Word Mark of Sony Corporation
Sundance Institute is not trademarked, but is used since 1981 by Sundance Institute, which hosts the Sundance Film Festival
Sundance Channel® is a Registered trademark of Sundance Enterprises, Inc.
TiVo® is a Registered trademarks of TiVo Inc.
VUDU™ is a trademark of VUDU, Inc.
XBOX® is Registered Trademark of Microsoft Corporation.
YouTube® is a Registered Trademark and Service Mark of Google, Inc.
Any trademark not listed out of oversight is a Trademark or Registered Trademark of it's respective owner.

Mention of any business in this article is not intended to endorse, disparage, or favor any business.

Movie names that are mentioned are not given reference citations. This is because numerous studios are involved in production, and they then assign distribution rights to multiple distributors, and these rights can be sold to other distributors. For production and distribution information on any movie mentioned, consult the Internet Movie Database, or other authoritative listing.

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