Bandwidth (video)
Video bandwidth is the amount of data a network connection can carry each second, measured in megabits per second (Mbps). It is different from bitrate, which is how much data a particular video stream needs each second. Playback stays smooth only while the viewer's available bandwidth stays above the bitrate of the rendition being played, with some margin to spare. On the publisher's side, bandwidth also describes the total data sent to viewers, which rises with every extra viewer, every extra minute and every step up the ladder.
Bandwidth vs. bitrate
Think of bandwidth as the pipe and bitrate as the water flowing through it. Bandwidth belongs to the connection: a home line, a mobile cell, an office network. Bitrate belongs to the stream: each rendition in a bitrate ladder is encoded to use a certain amount of data per second.
The two rarely match neatly. Most streams use variable bitrate encoding, so a fast action scene needs more data per second than a static shot, and short peaks can exceed the average. Connections vary too. A household shares its bandwidth across every device in use, and a mobile connection rises and falls as the viewer moves or the cell gets busy.
That is why players keep a margin. A rendition whose average bitrate uses most of the measured bandwidth will stall on the first dip. Choosing one that leaves headroom trades a little sharpness for playback that keeps going.
How much bandwidth does video streaming need?
It depends on resolution, codec and content. As a reference point, one large streaming service recommends a connection of 3 Mbps or higher for 720p, 5 Mbps for 1080p and 15 Mbps for 4K. Those figures include headroom above the streams' own bitrates.
Codec choice moves the numbers. HEVC and AV1 reach the same visual quality as H.264 at lower bitrates, so the same connection can carry a sharper picture, provided the device can decode them. Content moves them too. A static screen recording needs far less bitrate for a clean picture than a concert filmed under moving lights, which is why per-title encoding builds a different ladder for each video.
Frame rate and dynamic range add to it. A 60 frames per second stream needs more bits than the same picture at 30, and HDR renditions often need somewhat higher bitrates than SDR at the same resolution.
How does a video player measure bandwidth?
A player cannot ask the network how much bandwidth is available, so it infers it. Each time a segment downloads, the player divides the bytes received by the time taken. That gives a throughput sample. The player smooths recent samples, often with a weighted moving average, and treats the result as its bandwidth estimate.
The estimate is noisy. Very short segments finish before a connection reaches full speed, so they understate bandwidth. Segments served from the device's own cache, or from a proxy on the same network, can overstate it. A single slow request can drag the average down for several segments.
That is why most players combine the estimate with buffer level. If the estimate says a higher rendition fits but the buffer is thin, the player waits. If the buffer is full, it can try a step up and see whether throughput holds. Analytics tools record the same throughput per request, which shows what bandwidth viewers really get by network.
How much upload bandwidth does a live stream need?
Live video needs bandwidth in two directions. Viewers need download bandwidth, but the broadcast also depends on the encoder's upload, and every viewer shares that one leg. If it dips, the whole audience stalls at once.
The encoder sends a single high-quality feed, usually at or above the top rung of the ladder, because the service transcodes the lower rungs from it. The upload needs that bitrate plus audio, protocol overhead and a clear margin, since uplinks are often slower and less stable than downlinks. SRT adds retransmission traffic on lossy links, which needs headroom too.
Test the upload at the venue, not at the office, and at the time of the event, when other people on the same network are online. Use a wired connection where possible. For remote production, bonded cellular units combine several mobile connections into one. A backup ingest path, or an encoder that lowers its bitrate when the upload weakens, keeps a dip from becoming an outage.
How does FastPix handle video bandwidth?
FastPix shapes bandwidth at encoding, delivery and measurement. Per-title encoding builds a ladder that fits each upload, in H.264 and HEVC (H.265) as standard, with AV1 available on request, so a static screen recording is not given the bitrates of high-motion footage. Audio-only renditions are available for listening use. You can cap the top resolution at 720p, 1080p, 2K or 4K, which limits both what is delivered and what is stored. Renditions go out as HLS and DASH from 300+ points of presence, and FastPix Player switches between them with adaptive bitrate.
Posters count toward page weight too, and video and images can be served from your own custom domain. thumbnail images take a frame time, a width and height, jpg, png or webp output, and a fit mode such as crop, pad or intellicrop, a smart crop. A webp poster sized to its slot uses less bandwidth than a full-size frame, which matters on pages that show many posters at once.
Video Data shows the bandwidth viewers really have. Each view records request throughput, request latency, time-weighted average bitrate, upscale and downscale percentages and connection type, broken down by country, region, CDN, ASN and device. That shows whether the lowest rung is low enough for your audience's networks.
FastPix does not bill bandwidth by the gigabyte. Delivery is billed per minute watched, at a rate set by resolution, and volume discounts apply automatically. Audio-only renditions bill at a lower rate than video. Storage bills per rendition-minute and Standard encoding is free up to 4K. The free plan includes 100,000 streaming minutes a month.
By the numbers
- Netflix recommends connection speeds of 3 Mbps or higher for HD (720p), 5 Mbps for Full HD (1080p) and 15 Mbps for Ultra HD (4K). (Netflix Help: Internet connection speed recommendations)
