Like many other social networks, YouTube compresses each and every video that is uploaded into their database, to aid in storage space and video formats. YouTube channel owners also have the ability to download a copy of their uploaded video. But what happens if you upload, download and re-upload a YouTube video 1,000 times?
First of all, we have to understand the difference between a file format and a codec. A file format is the container or "wrapper" in which the audio and video exists. It is responsible for being recognisable to many digital video players, such as Quicktime and VLC media player, and with YouTube's preferred file format being an MP4. A codec, on the other hand, is the manner in which the audio and video is compressed, and YouTube makes use of H.264 compression.
An H.264 codec makes use of "block-orientated" frame compression, more commonly referred to as "inter-frame compression". This is where file space is saved by grouping frames together and isolating information in subjects that have no movement, such as a static background.
If an H.264 MP4 video file were to be re-uploaded several times to YouTube, you'll start to notice compression artefacts. These include severe chromatic distortion, softness and lack of sharpness, as well as distorted and muffled audio. All while still maintaining its original resolution by means of the number of pixels, height to width of each frame.
Well, YouTube makes use of a popular video compression codec, let's see how it goes!
Take a look at the video below by the YouTube channel: Marques Brownlee on This Is What Happens When You Re-Upload A YouTube Video 1000 Times?