Video On Demand
VOD (Video on Demand) services that let you watch the shows you want to watch whenever you want, such as Netflix, Hulu, and Amazon Prime, are popular.
In the past, PC-based devices such as PCs and tablets were required for viewing, but now it is possible to look directly into AV devices such as flat-screen televisions and video recorders.
Although it is such a VOD service, it was not seen with a large block noise at the beginning of playback, but after watching it for a while, the feeling of detail increased and after a few minutes the image quality became satisfactory. be all. That’s not the case with broadcast airwaves and record playback, but it’s weird when you think about it.
VOD services are available for direct viewing on AV devices such as flat screen televisions.
This “phenomenon that VOD video becomes beautiful during playback” is due to a technology called “ABR (adaptive bit rate)”. With the VOD service that supports ABR, the video quality can be adjusted according to the performance of the device and the speed of the communication line, and if the playability is considered to be the low / low speed line, the bandwidth (bit rate) of video will be reduced … On the other hand, if you know that the line has high playability / high speed, the bit rate will increase.
Immediately after playback, there may be little data buffered on the device side and the bit rate is set low, making image quality difficult. However, if the communication is stable and the video data buffer advances to a certain point, the bit rate will increase. Therefore, the image quality will improve after a while from the start of playback.
ABR supports many commercial VOD services along with “MPEG-DASH” transmission technology. The VOD service does not specify the playback device, and it can be said that it is an essential technology because it is not known if the communication line is Wi-Fi or cellular (3G / 4G) and if it is stable.
