Workflow of 4K Video Processing
Running a process of numerous operations is indispensable from the raw 4K video footage to the final presentation on screens. The digital 4K stream has to be demultiplexed to extract the particular video bitstream, which could be displayed on the monitor together with audio stream and side data information. Then 4K digital video is decompressed in a video decoder, and post-processed before displaying on the monitor, and finally encoded for storing in the storage media, playing on different screens, or transmitting to the communication channel.
As 4K videos can be wrapped in various forms, namely H.264 Video, MPEG-2 Video, MOV QuickTime Video HEVC/H.265 Video and so on, it's essential to decode 4K video streams into large amount of raw video frames before video processing. Briefly, decoding 4K footage take a process of opening 4K video to get 4K video streams, extracting the frames from streams, converting the YUV color space to RGB if necessary, decoding the frames and displaying on the monitor.
4K video post-processing generally refers to a process of all operations on video information, which is achieved through 4K video transcoding, compressing, adjusting and editing techniques.
Editing: 4K video editing is usually considered to be one of the most crucial parts of 4K videos post production. It's a process of splitting, integrating, and re-arranging 4K video footage to create a new work. 4K video editing includes cutting segments, re-sequencing clips, reducing noise, stabilizing shaky footage, adding transition, titling, correcting color and other special effects.
Compression: A minute of natural H.264 4K footage at 30fps can be 350MB on iPhone, which costs a wide bandwidth and brings heavy burden for storage. 4K video compression could reduce the 4K video size while maximizing visual effects through removing redundant information, including temporal redundancy between a set of key frames, and pixel-based spatial redundancy. Video compression ratio generally refers to the ratio of the data volume after compression to that before. The standard digital cameras have a compression ratio of 5:1, and some formats allow a video compression ratio at 100:1.
Lossless and lossy compression are terms that describe whether or not, in the compression of a file, all original data can be recovered when the file is uncompressed. When a file that has been compressed can be decoded back into its original form with zero loss of information, the compression is said to be a Lossless Compression. Lossy compression means the data after compression is not consistent with the original data. Almost all high compression algorithms apply lossy compression to achieve a lower data rate.
4K Video Scaling: 4K video processing also includes resolution scaling, frame rate conversion, enhancement, bit rate modulation, audio sample rate adjustment etc. Generally, 4K video parameters adjustment can greatly enhance quality, reduce file size to adapt to different screens or reduce the bandwidth consumption.
4K video encoding is the process of converting a 4K video from one format/codec to another, to make 4K video footage available to watch across different platforms and devices. Usually when the target device doesn't support the format that the original data is in, or the target device has a reduced capacity or the obsolete file type is incompatible on the modern new device, transcoding a format from one to another could make the 4K video available on the specific device with excellent compatibility. For example, H.264 4K video takes too much capacity compared with HEVC 4K, while it enjoys better compatibility.