Freeview Update: 7HD Sydney’s (sort of) Launch?

A few weeks back, a kind tweet from a reader let me know that 7HD Melbourne was on the air and broadcasting. While I was down in Melbourne, I wasn’t fortunate enough to be able to scrape together a transport-stream recording for analysis because of antenna and tuner issues, so I returned home underwhelmed, with the thought that I had missed an opportunity. The press generally seemed to imply that Sydney was among one of the cities that would have to wait for the launch of 7HD.

Interestingly, when I came home, and had a little time to decompress, I got out the tuner to find that indeed, the services on the air had changed, so it was worthy of a new reanalysis.

Results

station-wmarkUnlike that of Melbourne, 7HD in Sydney is a simulcast of 7mate, rather than the main 7 Sydney channel. As a result, it’s still mostly running the less interesting reruns. It seems that HD-worthy events may be casted on 7mate in the states where the new HD station is a simulcast of mate, otherwise on the main station where the HD station is a simulcast of the main station. At least, I hope that’s how it will work.

One piece of good news? The pesky TV4ME is now off the air, maybe for good. That gives us another 1.2Mbit/s or so back, so thank you!

As has been the main vein of the “HD revival”, the new stations all use H.264 encoding for the video. A few changes to PIDs occurred here and there, so the service table now looks like this:

ch7hd-svc-summary

Changes included:

  • Service names mostly changed to indicate the service area where it is broadcasted.
  • LCN70 is no longer a virtual service for LCN7/71, and instead maps to 7HD Sydney.
  • 7HD Sydney is a simulcast of 7mate, which is now converted to an MPEG-2 SD channel.
  • Text PIDs for 7mate, 7HD are changed, and AC3 audio is taken away from 7mate to 7HD Sydney.
  • As noted earlier, 7flix has gained an MPEG-1 Layer 2 128kbit/s Joint-Stereo stream to help alleviate the people who had vision but no sound, due to the choice of AAC-based audio initially. It was reported to have gone missing, but is back at last survey.
  • 7flix’s encoding profile has changed from [email protected] to [email protected] to gain a little more encoding efficiency, while being unlikely to provoke any compatibility issues.
  • Audio for the main channel is Joint-Stereo at the point I checked, but was claimed by others to vary continuously.
  • TV4ME is no longer carried.

Bitrate wise, things have been shuffled around as usual. The HD service is now receiving a very respectable ~7.4Mbit/s for the video stream alone, which is one of the best on the air at this moment because this is roughly the same bitrate the MPEG-2 HD service had but instead using a more efficient H.264 encoder.

ch7hd-bitrateevo

The rest of the SD channels have more or less been equalized to roughly 3.25Mbit/s total rate, and RACING.COM remains with its ~2Mbit/s allocation which has been unchanged since last year.

ch7hd-per-pid-rates

The per-PID rate tables are shown – total bitrates are a little off because it’s based on imprecise “to the minute” recording times, but on the whole, multiplex utilization has remained high with the null padding remaining relatively limited compared to previously when (seemingly) Fresh Ideas went off the air but the bitrate was not reallocated.

ch7hd-muxarea

The mux area chart shows that stat muxing is in use, likely in an effort to improve quality. The results above are from an average of 3 hours of programming in prime time (6:53pm to 9:53pm), and are more representative of the true average without instantaneous peaks and troughs.

Conclusion

It’s nice to see that high definition in its true and full 1080i form is returning to the air, with all commercial broadcasters switching over to H.264 encoding to meet quality and bitrate budgets. Of course, older sets (such as that in my hotel in Melbourne) and set-top boxes are not compatible with the more advanced codec and they will miss out on these new HD services, and lose HD service entirely, but this is the way of the future. I suppose it remains to be seen what ABC and SBS will do about their services and whether they will embrace H.264 encoding.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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