Recommendation ITU-T P.1204.4 describes the reduced-reference and full-reference video quality estimation model for Recommendation ITU-T P.1204 for monitoring the video quality for streaming using reliable transport (e.g., hypertext transfer protocol- (HTTP-) based adaptive streaming (HAS) over the transmission control protocol (TCP), quick user datagram protocol internet connections (QUIC)). The estimate is validated for videos encoded with H.264, H.265, video payload type 9 (VP9), or AOMedia Video 1 (AV1) codecs at any resolution up to 4K/ultra-high definition (UHD) (3 840 × 2 160) resolution for personal computer (PC) monitors and television (TV) and up to 2 560 × 1 440 for smartphone and tablet displays. The ITU-T P.1204 series of Recommendations provides sequence-related (between 5 s and 10 s) and per-1-second video-quality estimation. In principle, the per-one-second outputs of these video-quality models can be used together with an audio model for integration into audiovisual quality and, together with information about initial loading delay and media playout stalling events, further into a final per-session model output, an estimate of integral per-session quality (see e.g., Recommendations ITU-T P.1203, ITU-T P.1203.2, ITU-T P.1203.3). Recommendation ITU-T P.1204.4 was developed in collaboration with the Video Quality Experts Group (VQEG). This ITU-T P.1204-series of Recommendations addresses three application areas: –large-screen presentation as with fixed-network video streaming; –mobile streaming on handheld devices such as smartphones; –presentation on tablet-type devices.