This example shows how to use the DM642 EVM asynchronous scheduler and audio / video ADC and DAC blocks to generate an audio - video pass through system on your Texas Instruments™ DSP platform.
Available versions of this example:
The following figure shows the example model:
This example shows the use of DSP/BIOS™ Task blocks combined with Video ADC, Video DAC, Audio ADC and Audio DAC blocks to output sound and video synchronously. Two DSP/BIOS Tasks executing audio and video pass-through systems have been created to realize this model. Both Video ADC and Audio ADC are in blocking mode and each task will execute only when data is available on the respective ADC. The size of an audio capture frame is set to correspond to roughly 1/30th of a second to keep audio and the video synchronized. The DSP/BIOS task executing audio pass-through was set at a higher priority than the DSP/BIOS task executing video pass-through. This particular arrangement of task priorities means that audio task is able to preempt video task whenever audio data is available thereby ensuring the continuity of the sound at the expense of dropped or delayed video frames which are deemed to be less disturbing than a discontinuity in sound.
DM642 EVM board
NTSC video source
A/V connection cables
A microphone with a 3.5mm mini-jack
A pair a speakers or headphones with 3.5mm mini-jack
Connect a video source to the video port 0 (connector J15)
Connect a video display monitor to the video port 2 (connector J4) of the DM642 EVM board with an A/V cable
Connect 'Mic In' port (top part of connector J13) to the audio source
Connect speakers/headphones to the line out port (connector J14)
Open the model.
Open the Target Hardware Resources dialog and make sure that the specified CPU clock speed matches to that of your target board.
Click "Build Model" button to generate, build, load and run the DSP code.