Figure 1 categorizes the factors that impact a codec’s ability to help an organization
make or save money, with revenue factors on
top and cost factors on the bottom. While not
perfect, the color coding provides some measure of a codec’s proficiency with each factor,
with bright green being very good, the other
greens being good or OK, yellow being somewhat cautious, orange and light red being progressively more cautious, and red being poor.
Let’s start with H.264. In terms of reach, H.264
is tough to beat, with universal support in all
three categories. H.264 is also widely supported in live capture and transcoding, and low
latency, but falls off with high dynamic range
(HDR) video, where its 8-bit color depth limits its effectiveness.
On the cost side, H.264’s encoding time is
the fastest of the bunch, making it the least expensive codec to encode. The MPEG LA H.264
patent pool charges royalties for subscription
and pay-per-view streams, with H.264-related
lawsuits from Motorola and Nokia contributing to the FUD (fear, uncertainty, and doubt)
factor. That is, in 2017, Apple paid Nokia $2 billion as part of an H.264-related patent settlement, with more payments to come. Fortunately,
these suits appear to target encoder/decoder
usage rather than content-related royalties,
so they likely won’t impact most streaming
Although H.264 is inexpensive to deploy,
its relative compression inefficiency does de-
grade the quality of experience provided to
your viewers, particularly mobile consumers.
This is shown in Figure 2.
To explain, the figure shows two encoding ladders—on the left, H.264; on the right,
HEVC. To produce the ladders, I created optimal encoding ladders for each codec for the
videos Tears of Steel and Sintel and averaged
the result. Both sets are encoded for the data
rate shown on the left, and the resolution for
each that provided the highest quality at that
data rate for each codec. (For more on this Net-flix-inspired technique, check out the article
“Apple Got It Wrong: Encoding Specs for HEVC
in HLS” at go2sm.com/applewrong.)
The VMAF scores are computed using Video Multimethod Assessment Fusion objective
metric, the quality gauge used by Netflix in
its per-title encoding (and shot-based encoding) techniques. The Delta column shows the
difference between the VMAF scores for the
H.264 and HEVC streams. Note that, according to the metric, a difference of six VMAF
points equals a “just noticeable difference,”
Figure 1. This scorecard shows the strengths and weaknesses of the four leading codecs.
for H.264 and
HEVC. Note that
the highest quality
streams (the bottom
three in the chart)
for HEVC are the
same 1080p stream.