What is Advanced Video Coding? (AVC Explained)

What is Advanced Video Coding (AVC)?

AVC, or Advanced Video Coding, refers to the file format or a standard for storing video contents. Usually, this video compression standard uses much lower bit rates as compared to the earlier standards while encoding high-quality videos.

Technically, it is a method where an encoder changes the video into a compressed format and a decoder converts it back to the original. It follows a prediction process to encode and transform to create a compressed H.264 bitstream.

KEY TAKEAWAYS

• Advanced Video Coding refers to the industry standard for compressing and encoding video content.
• Video frames are processed in this method by using block-oriented motion compensation.
• The macroblocks used in AVC usually consist of 16 x 16-pixel samples, divided into transform blocks and further into prediction blocks.
• The resolutions recognized by AVC are usually up to 2048 x 2048 pixels.
• This H.264 algorithm reduces bitrates substantially, making the images look better after transmission.

Understanding AVC (Advanced Video Coding)

Advanced Video Coding, also referred to as H.264 sometimes, is a standard video encoding and digital video compression format.

This specification was designed and developed in 1998 jointly by the Moving Picture Experts Group (MPEG) and the International Telecommunications Union (ITU-T). However, its official approval came in, and it was launched in 2003.

This standard, however, does not stipulate the algorithms for encoding video contents. It is for the manufacturers to decide. The use of AVC is also free to the users.

Versions and formats

There have been different versions of AVC launched over time, ranging from Version 1 to Version 27, since it was first launched on May 30, 2003.

It is also designed and used in different derived formats by different manufacturers, such as:

• AVCHD, the high-definition recording format created by Sony and Panasonic
• AVC-Intra, the intraframe-only compression format created by Panasonic
• XAVC, the recording format created by Sony

Uses

Today, this specific video compression standard is used by almost all streaming protocols in the world. This includes, but is not limited to, the following:

• The Real Time Streaming Protocol (RTSP)
• The HTTP Live Streaming (HLS)
• The HTTP dynamic streaming (HDS)
• The Dynamic Adaptive Streaming over HTTP (MPEG-DASH)
• Cloudflare Stream

Out of the above streaming protocols, HLS in particular works only with AVC, while the others still support different video compression standards apart from H.264.

The AVC specification is most commonly used to set the typical syntax for video formats used in:

• Blu-ray discs
• Teleconferencing and videoconferencing
• CD/DVD content distribution
• Digital broadcasting and mobile TV
• Internet Protocol Television (IPTV)
• Streaming video on Internet Over-The-Top (OTT) platforms
• Cable and satellite Standard Definition and High-Definition linear broadcast

Objectives

The main objectives for designing this particular standard are to offer:

• Better compression performance
• Higher quality images
• Lower compressed bitrate
• Superior transmission support
• More flexibility
• Wider variety of compression tools

Characteristics and features

The files stored in this particular format have a lot of similar characteristics of the MP4 files with reference to the methods for:

• Storing data
• Optimizing data
• Compressing data

It is because of these similarities that the AVC files are often considered to belong to the MP4 family.

However, as the experts point out, H.264 is an outstanding alternative to the MP4 format. This is because, when the two are compared, AVC seems to beat the latter in several aspects, such as:

• It has a higher compression ratio.
• It supports longer encoding.
• It has better storage efficiency.

However, it needs greater central processing power.

Features

There are a few notable features included in the AVC standard, such as:

• Loss suppleness
• Slice switching
• Video Usability Information (VUI)
• Multi-picture and inter-picture prediction
• Lossless coding of macroblocks
• Motion compensation for variable block sizes
• Supplemental Enhancement Information (SEI)

Encoding and decoding

The actual job in AVC is done by the encoder and the decoder. Here, the encoder works in three discrete phases, such as:

• Predict
• Transform
• Encode

On the other hand, the decoder produces the final video output by following the other complementary processes, which include:

• Decoding the format
• Inverse transform
• Reconstruction

The underlying mechanism of AVC breaks the video content down into some sort of a machine language. This allows it to be stored and accessed easily by a wide range of diverse technologies.

Profiles

AVC defines profiles, or sets of capabilities, for identifying the requirements of different bitstreams.

Though the most common profiles used in the high profile, there are also a few other significant profiles used, such as:

• Multiview Depth High Profile
• Extended Profile
• Stereo High Profile
• Baseline Profile
• Constrained Baseline Profile
• Main Profile
• Progressive High Profile
• Constrained High Profile
• High 10 Profile
• High 4:2:2 Profile
• High 4:4:4 Predictive Profile
• High 10 Intra Profile
• High 4:2:2 Intra Profile
• High 4:4:4 Intra Profile
• CAVLC 4:4:4 Intra Profile
• Scalable Baseline Profile
• Scalable Constrained Baseline Profile
• Scalable High Profile
• Scalable Constrained High Profile
• Scalable High Intra Profile
• Stereo High Profile
• Multiview High Profile
• MFC High Profile
• MFC Depth High Profile
• Multiview Depth High
• Enhanced Multiview Depth High Profile

Can AVC be Uploaded to YouTube?

Usually, no. If you have shot a video with your HD camcorder, which typically supports files in AVCHD format, you will not be able to upload it to YouTube because the channel does not support it.

You will actually need to convert it into a format supported by YouTube, following the specific encoding settings recommended by the channel for their optimal conversion.

If you do not know which specific file format you should save your video file in so that you do not get an error message saying “invalid file format” while uploading it on YouTube, here is the list of supported formats:

• AVI
• CineForm
• DNxHR
• FLV
• HEVC (H.265)
• MOV
• MPEG-1
• MPEG-2
• MPEG4
• MP4
• MPG
• MPEGPS
• ProRes
• WebM
• WMV
• 3GPP

So, go ahead and convert your AVCHD file into one of the above formats and share it on YouTube.

The process is simple when you use a reliable third-party AVCHD to YouTube converter.

AVC Vs HEVC

• In AVC, video frames are typically processed by using macroblocks. On the other hand, HEVC or High Efficiency Video Coding processes the information by means of Coding Tree Units or CTUs.
• The file sizes in AVC are usually larger than the file sizes in HEVC because the latter uses CTUs.
• In terms of efficiency and bandwidth use, AVC seems to lag a bit behind HEVC.
• The spatial prediction as well as motion compensation are also better in HEVC rather than in AVC.
• The AVC technique does not need as advanced hardware as HEVC for processing the information.
• Data is compressed more efficiently in HEVC than in AVC, which improves the quality of broadcast and reduces buffering or lagging.
• In terms of compatibility with browsers, AVC is typically compatible with almost all available browsers. On the other hand, HEVC is compatible with just a few specific browsers.
• The time taken for encoding in AVC is anywhere from 2 to 15 times shorter than the time taken for doing the same task in HEVC.
• With respect to the encoding quality, that of the HEVC is better than the AVC.
• The encoding, transcoding and storage costs in the case of AVC are much lower than those of HEVC since the latter takes much more time to do the same job.
• AVC is good to use in low latency applications, but in comparison, HEVC is good to use in 4K and High Dynamic Range (HDR) video applications and the Dolby Vision bitstream profile.
• When compared with AVC, it is easier to reduce the bitrate and improve coding efficiency in HEVC since it offers different tools for doing so.
• AVC is more popular than HEVC as nearly 70% to 80% of videos all over the world use AVC.
• In AVC, a block size of 16 x 16 is used, but in comparison, the block size used in HEVC is 64 x 64.
• The prediction units in AVC are 16 x 16 to 4 x 4, but in comparison, the prediction units of HEVC are 64 x 64 to 4 x 4.
• The transform unit in AVC is 8 x 8 to 4 x 4, but in comparison, that of the HEVC is 32 x x32 to 4 x 4.
• While there are 9 intra modes in AVC, there are 35 such modes in HEVC.
• The AVC has 7 inter modes, but in comparison, HEVC has 24 inter modes.
• In AVC spatial media motion prediction is followed, but in comparison, HEVC follows advanced motion vector prediction, both temporal and spatial.
• The subpixels in AVC are 6 tap Luma and Bilinear for Chroma, but in comparison, those in HEVC are 7/8 Tap Luma and 4 Tap for Chroma.
• In AVC, a deblocking filter is used for reverse transformation, but in comparison, HEVC uses an unblock filter and SAO filters for the same.
• The color depth in AVC is 8 bits, but in comparison, the color depth in HEVC is 10 bits.
• For entropy coding, AVC involves Context Adaptive Binary Arithmetic Coding (CABAC) or Context Adaptive Variable Length Coding (CAVLC), but in comparison, HEVC uses only CABAC with parallel operations.

Does AVC Support 4K?

Usually, no. The regular AVC standard supports MPEG-4 at its highest level.

However, the XAVC version may support 4K resolution, which is either 4096 × 2160 pixels in the digital cinema sector or 3840 × 2160 pixels in UHD, at a maximum of 60 Frames Per Second (fps).

Conclusion

Advanced Video Codec, also commonly referred to as H.264, is a specific type of format or standard for video compression launched in 2003 and used widely for Hi-Fi video recording, compression, and broadcasting.

It is usually the codec for Blu-ray discs but is also used in modern video recorders (DVRs) as the main codec.