Please find the answers to your questions below:
1. Packet per Xfer is used to set the number of packets that you wish to send or receive using the streamer application. Xfers to Queue sets the total number of such transfers that can be queued using the streamer Application.
2. To understand how the Failures counters are updated, please refer to the the Form1.cs file which can be found in the following location:
C:\Program Files (x86)\Cypress\EZ-USB FX3 SDK\1.3\application\c_sharp\streamer
3.The example project USBIsoSourceSink makes use of a DMA MANUAL_IN channel and a DMA MANUAL_OUT channel. Any data received from the host through the DMA MANUAL_IN channel is discarded. A constant data pattern is continuously loaded into the DMA MANUAL_OUT channel and sent to the host.
For this, we have configured the size of DMA buffer to be 24kB. Each ISOC packet is of 1KB. So there can be 24 packets per buffer. Now refer to the following code snippet.
This is used for preloading the DMA buffers. You can see that the highlighted for loop fills 1kB of DMA buffer with a constant pattern. The constant pattern is AA initially. In the next iteration, it will be AB and so on until 24kB is filled. After the buffer is filled, it is committed to the host.