DVB Digital station logo subtitles into the system is pre-made icons or text message a good selection of MPEG-2TS plug into the flow of program Video Image, the television network company to achieve station logo, insert a business angle standard or subtitles. DVB digital station logo into an existing way to achieve three main types: subtitle mode, the whole series full explanation of the method, the local decoding method.
Which, subtitle the most simple way, without adding new equipment, disadvantage is STB Must support the subtitle decoding, and many special effects station sign subtitles can not be achieved.
Way the whole series all solution to the original analog station logo CG Improvement. Namely: the reduction of the current digital signal into an analog signal, analog sets standard way to join the CG station logo or title, then translate digital signals. This approach has the advantage of mature technology, low cost, disadvantage is the need to decode – the process of re-encoding, signal a loss.
Local codec is totally based on digital signal processing method. TS stream directly to the video to change the macro block pixel hybrid DCT frequency domain calculation, in the TS stream to station logo, flying characters, weather, angle standard, Animation , Back-up pictures embedded. Advantage is not treated, some of the original signal will not be any impact will not be signal loss, disadvantage is the higher skill level required, the higher the cost of the corresponding.
Coding algorithm essentially, through the process of compressing video signals. In the larger of the compression ratio will cause a small amount of signal loss. Is a lossy compression.
The station logo subtitles machine, the best approach is to insert a station logo or title of the regions of partial treatment, so that will not affect the overall quality of the picture. The whole solution in the whole series of products is once again the signal decoding and encoding, the process will lead to signal loss again. Especially the repeated “decoding – code”, the signal loss is particularly serious.
In addition, you can see from the chart, the Taiwan standard CG and encoder, multiplexer is a series of relationships. So, if TS stream full decode – re-encoding, the entire TS stream signal quality will depend on the encoder and the station logo in the coding performance subtitle machine both the weaker party. The general solution in the whole series products are mostly all options are based on server or IPC soft coding, the coding results are far inferior to the professional encoder. So, will result in decreased overall signal quality.
The following, on the whole series full explanation of the method, the local decoding means to achieve these two technologies means of a simple contrast.
Whole series full explanation of the method. ASI card inserted by way of industrial control computer, according to the number of configuration ASI card device can determine a way or a few road shows to station logo insert subtitles. To configure an ASI card, for example, processing steps are:
1.’s A way to input TS stream multiplexer.
2. On the need to insert a set of programs to decode.
3. The decoded analog signal station logo or title of the insert.
4. To complete the insertion of the analog signal to encode.
5. To complete the program and the other untreated into the program as a way to re-multiplexed TS stream. Output.
The device in achieving the station logo subtitle insertion, on the TS stream to demultiplex, multiplex, on the program within the TS stream to decode, encode. Because for each of the CAO can not be undermined, the price is the deadweight loss of the original signal quality. TS streams on the one way to select a set of programs for station logo subtitles into relatively simple. However, if you want to stream TS on a road all the programs from the station logo to insert subtitles and its treatment will be very complicated.
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