Why is BBC HD's bitrate so low?

To give some examples, last week’s His Dark Materials is 1924MB for a 58 minute programme (or ~33.2MB/minute), and War Of The Worlds (drama) is a little less at 1518MB for its 56 minutes (~27MB/minute).

By comparison, some random testing shows S4C HD running at ~83MB/minute (which would be ~4833MB for a 58 minute runtime), NHK World a little less at ~78MB/minute (~4524MB for 58 minutes), and ITV HD offers ~69MB/minute (~4021MB for 58 minutes for comparison). That ITV’s bitrate is twice that of the Beeb… ought to be embarrassing.

To a degree, this is a good thing for me as I can record hour-long programmes and they will be under 2GiB, but it does seem a little odd that what is supposed to be Britain’s leading broadcaster and it’s flagship channel… has such a poor bitrate.

I’m not complaining – it’s better for recording content. I can get those entire programmes in one go, under 2GB an episode. This afternoon I’ll be watching/recording JESC on S4C, and doing it SD because for a programme expected to run to 145 minutes, the SD version is expected to run to about four and a half gigabytes (so will need to be split; easy enough, do the songs and then do “everything else”). The HD version? If it maintains that bitrate, we’re looking at around 12GB for the broadcast! It’s perhaps worth adding that S4C’s SD bitrate (~34MB/min) was measured as higher than BBC HD! Um.

It’s not a question of audio channels either. S4C has English and Welsh, obviously, but then when the video player in my phone misread the audio ID in War Of The Worlds, I discovered that it has an English audio track, and a “described” audio track for visually impaired people.

So… why is BBC’s HD bitrate so much less than everybody else’s?

And while we’re at it, why does BBC SD offer teletext-style subtitles and embedded (DVB) subtitles; while BBC HD offers only teletext style subtitles?
It’s a bit hit and miss as to whether my phone’s player will accept the teletext type (His Dark Materials, not yet; War Of The Worlds, yes); but while the embedded captioning can be overlaid on the picture as is usual these days, the teletext style subtitling looks exactly like what you would imagine. Big bold blocky low-res letters on a solid black background. It’s weird to have an HD image with captions that are a throwback to the eighties.

My Kodi box (Wetek Play) has recorded the first three episodes of His Dark Materials at 1.74GB, 1.72GB & 1.6GB off air (Freeview HD) with a five minute overrun. Are you seeing anything better/worse in terms of picture quality between the different bitrates?

I’m not sure if it depends on the feed, but the BBC’s idea of iPlayer HD streaming was/is 720p. The Freeview feed is 1080i, if memory serves, compressed to a 8-10 Mbit envelope. Freesat increases that to around 20 Mbit AFAIK.

If it was the 720p iPlayer feed, then the smaller file size would fit. I know my iPlayer app still switches to 720p when playing Name of the Rose.

I’m just watching a US TV show on blu-ray and they squeeze 6 episodes plus deleted scenes per disc, so I’d say roughly 8GB per hour. Blu-ray is usually about twice the “necessary” bandwidth for agreeable 1080p viewing (at normal view distances, on 40-60" TV), which is why it looks better than streaming services which are typically lower than the agreeable level, but still adequate. I think Netflix 1080p runs with an adaptive 8-12 Mbit envelope for 1080p, by comparison.

So, by those yardsticks, S4C HD should be very agreeable, almost approaching blu-ray quality to a casual view, whereas BBC would look very “streamed”. But, it would be bang-on for 720p.

BBC’s idea of iPlayer HD streaming was/is 720p

It still is. At least, that’s what get_iplayer spits out so I presume that that’s the best available.

I’m not sure if it depends on the feed,

Remember I live in France. It’s satellite only, from the 28E pile that serve FreeSat/Sky.

The image is 1920×1088 (1080i) with frequent visible honeycombing on fast motion on contrasty areas, so much for progress. ;-)

All of my file sizes for determining bitrates were performed using recordings from the satellite receiver, that basically dumps the entire TS stream as received (including multiple subtitles and audio tracks if available).

Are you seeing anything better/worse in terms of picture quality between the different bitrates?

Possibly. While the BBC feed is generally “okay” (see below), some programmes, notably War Of The Worlds, has large areas of similar colour (like fog, smoke, dark corridors…) and these are rendered as several distinct bands of colour instead of as a natural fade. There was quite a prominent one this week, I can try for a screenshot tomorrow if anybody is interested.

As for saying it is “okay”, please note that I don’t have an HD television. My setup is the satellite receiver, in SD or HD mode, outputting CVBS (576i with electric schoolgirls) to a gadget that translates this to analogue VGA for watching on a 1440×900 monitor. It actually does a pretty decent job of upscaling, and there’s no noticeable lag on the video while all this is happening.
While that monitor is large enough resolution to cope with standard HD, either it isn’t able to cope with the frame rate that broadcast television uses, or the HDMI to VGA adaptor can’t do 50Hz. I don’t know which, but I know trying to convert HD (720p) directly to VGA didn’t work. Oh well…

Blu-ray is usually about twice the “necessary” bandwidth for agreeable 1080p viewing

Remember, you’ll need more bandwidth for 1080p than for 1080i, so that’s not a surprise.

Sounds a lot like the Beeb are just putting the Freeview broadcast feed onto the higher-bandwidth satellite feed then, squandering the extra space available. I suppose that’s the cheap’n’cheerful way to do it!

Quick thought – are DVB-S2 broadcasts all MPEG2 still, or AVC (h.264)? It’s ages since I checked broadcast TV streams. Most blu-ray and streaming services will be AVC based, with HEVC for 4k.

The reason I ask is that if you double up that 1080i feed size (4GB) as a guesstimate for 1080p instead of interlaced (probably not good maths) it should be fairly decent. BUt, if it is MPEG2, then the compression will be considerably less efficient, in which case all my “back of a postcard” maths goes out of the window.

then squandering the extra space available.

Does it not allow more channels to be multiplexed onto the signal?

are DVB-S2 broadcasts all MPEG2 still, or AVC (h.264)?

SD is MPEG-2, and likely will be for quite a while due to the number of receivers that support it.
HD is AVC. Not just because better compression, but also because IIRC, there’s no official MPEG-2 DTV support for pictures of that resolution outside of HD camcorders of the mid 00s and the failed HD-DVD.

Dous it not allow more channels to multiplexed onto the signal?

Yes, but is this something we expect the Beeb to suffer from?

Could be… The transponder at 10847V carries BBC1, 1NI, 2, 2 Wales, and CBBC in HD with a 23000 symbol rate. That’s five channels. ITV has the same symbol rate and shares itself with three other channels, but a 1/5 extra bandwidth doesn’t count for the near double bitrate. One assumes the other ITV regions are also of a higher bitrate too.

Sounds a lot like the Beeb are just putting the Freeview broadcast feed onto the higher-bandwidth satellite feed then

This is probably the most likely explanation. :-)

iPlayer video has always been grotty. But that (dreadful) War of the Worlds miniseries is smeary and juddery too. I can’t work out whether they tried some kind of 24 frame effect on it.

I’m currently Jeff Wayning it out of my short-term memory so I’ll not mention it again. UULLLAAAAAA.

Remember, you’ll need more bandwidth for 1080p than for 1080i, so that’s not a surprise.

That entirely depends what your source signal actually is – if it is e.g. Blu-Ray 1080p24, you might find out that converting that to 1080i50 or 1080i60 ends up needing more bandwidth.

But that (dreadful) War of the Worlds miniseries

Yes… I like the lead female (and think all the lead males need to have some sense beaten into them with a large claw hammer), but I’m still trying to work out if it’s supposed to be some sort of weird romantic drama. I expected Martians, flailed bodies, gore… you know, the sort of thing befitting a 10pm programme about a Martian invasion. And since it moves almost at Twin Peaks pace, they’re going to have to cover a lot of ground next week given it’s a three-parter. Or do an ass pull and finish part way through with a “to be continued”.

is smeary and juddery too.

I think most of the world believes that “adds tension” after the X-Files went to town with “running in circles around the same bit of woods at night”.
You know why The Blair Witch was so popular? They totally shook it up – they had “running in cicles around the same bit of woods in the daytime”!

I can’t work out whether they tried some kind of 24 frame effect on it.

Obligatory XKCD quote: We’re also stuck with blurry, juddery, slow-panning 24fps movies forever because (thanks to 60fps home video) people associate high framerates with camcorders and cheap sitcoms, and thus think good framerates look ‘fake’.

I’m currently Jeff Wayning it out of my short-term memory so I’ll not mention it again. UULLLAAAAAA.

Oh come on, even if Amy and prat-face loosen their corsets and grope for the next half hour of runtime, it will still be better than that awful American film. And I don’t mean the Tom Cruise one. Here’s a screenshot to remind you:

If you haven’t actually seen this one…
…don’t.

A lot of the stuff over the last couple of years appears to have been recorded (but probably not ‘broadcast’) in 4K. I’m sure the DA ‘Seven Worlds…’ series is in 4K.

I’ve recorded, but not watched WotW yet. I like the idea that they are doing it (mostly) according to the book. At the time I read it (70’s), I was living in Woking and there’s even mention of the place I lived, so it holds special memories for me.

don’t

That version takes a number of liberties with the book, but it has to be judged by the standards of its time – it was released the same year as “The Beast From 20,000 Fathoms”, “It Came From Outer Space” and “Invaders From Mars” after all…

Compared to them, it’s superb. And still better than the Tom Cruise version.

However, the following year another “20,000” was released, but I’ll say no more about that.

If you haven’t actually seen this one… …don’t.

Do. It’s in my top 3 S-F movies from the 50’s along with “The day the Earth stood sill” and “Forbidden Planet”.

Was it Impression that would error with “Klaatu barada nikto” under some circumstances, or was it InterWord?

If you really want a travesty with the “war of the worlds” branding, try (or don’t!) the 1990 US TV series. It is designed to be a follow-on from the old movie, and the first series is more-or-less watchable, but by the second, it had been taken over by the people behind (I think) the Friday 13th horror shows and changed completely turning into a gore-fest – to quote wikipedia “pushing the limits of acceptable TV broadcasting”. I stopped watching after a particularly unpleasant episode in a maternity hospital.