In the past I've tried to characterise the streaming behaviour by streaming HD recordings from a DP-S1 to a DP-H1, and noting whether the (short) trials were successful or not.
This time, I've measured the streaming bitrate by copying a recording from the DP-S1 to a Mac, via WizPnP using getWizPnP. getWizPnP simply tries to read the WizPnP stream as fast as possible. I don't know how well this represents the streaming done when streaming to a Beyonwiz WizPnP client, but the streaming probably can't go any faster.
While this method doesn't give a direct indication of whether streaming will work or not, it's more flexible, since if you know the bitrate of any media file, you should be able to compare it with the bitrates in the table.
Bitrates and server load for WizPnP data transfer
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+--------------------------------------------------------------------------+
| WizPnP average throughput Mib/s (01.05.280) |
+-------+----------------+------------------------+------------------------+
| | In Menu | Watch HD | Watch HD, record 1 HD |
+-------+------+---------+------+---------+-------+------+---------+-------+
| Video | No | TS | No | TS | Watch | No | TS | Watch |
| out | TS | enabled | TS | enabled | TS | TS | enabled | TS |
+-------+------+---------+------+---------+-------+------+---------+-------+
| | | | | | | | | |
| 720p | 24.8 | 24.0 | 22.4 | 18.4 | 12.8 | 16.0 | 14.4 | 9.6 |
| | | | | | | | | |
|-------+------+---------+------+---------+-------+------+---------+-------+
| | | | | | | | | |
| 1080i | 24.8 | 24.0 | 21.6 | 18.4 | 12.8 | 16.8 | 13.6 | 8.8 |
| | | | | | | | | |
+-------+------+---------+------+---------+-------+------+---------+-------+In Menu means that the Beyonwiz is displaying the Setup menu.
Watch HD, means that the TV is decoding the service to the screen. For these tests, Prime HD (1440x1080p, 13.6MiB/s).
Watch HD, record 1 HD means that in addition to decoding TV, another HD service is being recorded. For these tests SC10 HD (1920x1080i)
No TS means timeshifting is disabled.
TS enabled, means that timeshifting is enabled, but Live TV is being watched.
Watch TS means that the TV service is being decoded from the timeshift buffer.
Other server loads.
The table is not comprehensive of all server loads. I have assumed that streaming two simultaneous HD recordings will never be feasible. Two SD recordings may be under some circumstances (needs about 12-13Mib/s total throughput).
Chase-play with only one recording running should be similar to Watch HD/Watch TS.
Viewing a recording while recording another service should be similar to Watch HD/Watch TS (TS is temporarily disabled by activity).
Chase-play of one recording while recording two programs should be similar to Watch HD, record 1 HD/Watch TS (TS is temporarily disabled disabled by activity).
Viewing a recording with no other activity should fall between Watch HD/No TS and Watch HD/Enable TS (TS is temporarily disabled disabled by activity).
Typical HD data rates.
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+----------------+-------------------+-------+
| Typical HD service bitrates MiB/s (Nov 08) |
| (Canberra Black Mountain) |
+----------------+-------------------+-------+
| Service | Resolution | Mib/s |
+----------------+-------------------+-------+
| SBS HD | 1280x720p | 8 |
| ABC HD | 1280x720p | 10 |
| WIN TV HD | 1440x1080i | 11 |
| SC 10 HD | 1920x1080i | 14 |
| PRIME HD | 1440x1080i | 14 |
+----------------+-------------------+-------+Similarly, it should be possible to tell whether other media types can be streamed under a given server load. I'd be very interested in hearing whether the table predicts the actual streaming of video well, or not.
Technical notes
- The data transfer rates were gathered by the (yet to be distributed) getWizPnP 0.3.3, on an iMac G5 2GHz, 1.5GB memory, copying in Beyonwiz recording format to a Firewire connected WD MyBook Home Edition 500GB HDD.
- The data rates are Mib/s, mebibits/sec. 1 Mi = 2^20 = 1024*1024 = 1048576. 1Mi ~= 1.05M. Take care when comparing these bit rates with Mb/s 1Mib/s ~= 1.05Mb/s.
- The actual data precision is +-0.8Mib/s, converted from +-0.1MiB/s.
- The recording transferred was 5 minutes of ABC HD, 370MiB. The video format is unimportant, because it was simply being copied, not decoded.
- The numbers quoted are averages for the whole transfer. The actual transfer rate at any instant varies about the average slightly. The important figure for transfer rate is the minimum rate after averaging over the streaming buffer size on the WizPnP client, but its size is unknown.
- The transfer rate at the start of the transfer is often much lower than the average. It's uncertain whether this is a genuine phenomenon, or a bug in getWizPnP's sliding average calculation. The overall average transfer rate is not affected by any miscalculation in the sliding average.
- The time shift lag for Watch TS was short and not carefully controlled.
- Posts of transfer rates for other Beyonwiz servers and for other server loads are most welcome.
- The streaming rate changes between when the Beyonwiz is outputting 720p or 1080i are very small.
