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I hope it is within the board rules to make this request.
I feel that the sort of programmer/developer who might have the interest and skills for our project might well be someone who knows virtualdub.
We work in Asia
We have a client who is building up to 1000 low-cost meeting halls as part of a government-sponsored public education program.
Whilst the hall is multi-purpose, one of its chief requirements is as a 'cinema', showing both entertainment and public education films.
We are only concerned with the 'cinema' aspect of the hall.
These meeting halls will be distributed around the country - mostly in rural areas. There will sometimes be little infrastructure there. We cannot rely on anything other than a basic electricity supply (which may cut out frequently, requiring a good UPS), and access to a satellite signal. There will be no access to ADSL or GPRS signals.
High definition H.264 transport streams will be beamed by satellite into these 'cinemas', stored on a small digital set-top box, and played out according to a pre-defined schedule.
We are making use of mostly quite cheap home products to achieve this. The budget is very low. But we can still maintain a very high standard of sound and audio presentation.
But we have a challenge.
The brief requires that the cinemas be entirely unmanned.
The whole operation must be automatic, as we will have no way of training or ensuring the skills of the regional operators. They will have little or no technical ability, and its important that the show goes on, regardless of the local operator.
There are four elements to the automation:
1. The film must start and stop at the right times.
2. The lights in the hall must dim on and off at the right times.
3. A small computer monitor positioned outside the hall must show:
a. Information about how long before the start of the next programme - probably a countdown.
b. Text information about upcoming programmes.
For item 1, this is simple. The satellite service provider provides the uplink, the satellite dish, the set-top box etc. They have already been contracted, and they have the ability to send control signals to their playout box. (They have no ability to send out any external control or data signals.)
So we do not need to worry about this.
But items 2 and 3 are our responsibility.
The cinemas do not have any 'data' link or modem.
The signal sent to the cinemas by satellite cannot include a data signal or cueing signals. It contains only a Transport stream which will go to the settop box and be decoded to an HDMI video signal and an optical digital audio signal.
After much thought, we feel that the only way to send the required cues for lighting automation and simple text information will be by embedding it in the audio and video signal in such a way that it will be passed through the whole chain, and can be read at the cinemas either in the video or audio signal.
One option is to use one of the audio tracks of the incoming stream to carry this data information.
The advantage of this is that the hardware for a small PC to read this audio track and convert it into data would be quite cheap.
However, our brief is to provide 5.1 surround sound to the cinemas. So if we used one track for the data signal, we would lose one channel of audio, and this would not be acceptable to fulfil the brief. Something like 6.1 would be great, but utterly non-standard and we then couldn't use standard equipment - so we considered this impractical.
So we have abandoned this concept.
We then considered the VANC signal portion - often used for closed captioning.
We are still considering this, but we have conflicting information as to whether an HDMI cable can carry a VANC signal, and we are not sure whether this signal will be passed through the entire satellite chain.
So ultimately, we feel there is only one absolutely certain way:
The picture will be projected onto a screen which will have a black mask.
By zooming in very slightly, it would be very easy to ensure that the top two or three lines of the HD picture are not displayed on the projection screen.
We could include data in these top lines.
Given that they are part of the picture itself, the H.264 encoding, the satellite chain, and the set-top decoder must include these lines.
But we would need a customised way of doing this:
1. Software or virtualdub filter which can take a text 'script' including timing information and encode this into the top lines of the video picture before it is H.264 encoded. Obviously the data must be resilient and redundant enough to be able to withstand the H.264 encoding. However, the quantity of data to be carried is very small. This information would need to be inserted at various points in time along the video signal (rather than simply as a header) so that it can trigger automation and text display events at the appropriate time relative to the video picture.
2. Software running on a cheap PC at the client end, which can read the picture from a cheap HDMI video input card, decode it, and pass it out as close as possible to real-time.
3. We will require programming which can accept the decoded text and store, display it, or use it to control the X10 automated lighting system.
The ideal programmer must have experience and knowledge of video signals, available SDKs, and programs such as virtualdub.
Being a public supported project in a developing country, the budget is very small.
If anyone is interested, they can contact me to discuss.
Obviously we need someone with experience of video signals, coding, compression, etc.
We would need to find a decent HDMI card which also has an SDK (possibly the Intensity Pro)
And we would need to evaluate the cost of the system development, and whether it is viable.
Thank you for your time.
Paul Spurrier
paul@paulspurrier.com |
