5 Replies Latest reply on Oct 20, 2019 10:37 PM by YashwantK_46

    FX3 SD video encoder



      I'd like to interface FX3 with an Standard resolution S-VIDEO encoder (Analog device ADV7280A)


      I need some advice in order to modify the UVC AN75779 to works with a Interlaced video signal.

      At the moment I'm able to get a 720x288 video.


      I think there are some modification to do in the payload header and to the configuration descriptor.

        • 1. Re: FX3 SD video encoder



          If you are looking to change the streaming resolution please refer to this Knowledge Based ArticleChange Resolution in FX3 UVC Camera - KBA220269 which addresses the modifications to be done in AN75779.


          Best Regards,


          • 2. Re: FX3 SD video encoder

            Hi Yatheesh,

            no my problem is to find the right configuration description and payload behaviour for a 2 FIELD interlaced Frame (PAL 720x576 / 25fps).

            there are two FIELD at 720x288 / 50fps (right and left).

            • 3. Re: FX3 SD video encoder


              Can you please be a little more clear on what you intend the FX3 to handle?

              Like what should the exact behavior of FX3 be inorder to handle the data that it is getting from the video encoder?


              Is it like, you need FX3 to just commit the encoded data form the encoder and commit it to the host ?

              Can you please explain what you mean when you say 2 FIELD interlaced Frame?




              • 4. Re: FX3 SD video encoder

                Hi Yashwant

                I have a digital video signal with the following spec:


                16bit BT656 YCBCR interlaced--> interlaced = one filed has the odd line of the frame, one field has the even line of the frame

                the Frame speed = 25fps (-> 2 field at 50fps)

                The inteface used is GPIF2, the state machine is the same used in the appnote  AN75779.


                I'm able to stream the video to the PC but the UVC configuration descriptor and payload (my question) have to be arranged in order to manage a INTERLACED Video format.



                • 5. Re: FX3 SD video encoder



                  Inorder to have the interlaced data coming into the FX3, please download the USB Video Class 1_5 from here.

                  Please refer to Table 3-1 Frame Based Payload Video Format Descriptor in the document:

                  USB Video Class 1_5/USB_Video_Payload_Frame_Based_1.5.pdf

                  and check the offset 25 'bmInterlaceFlags' and change the value of that in the descriptors in AN75779 firmware according to the video input stream to the FX3 from the video encoder.


                  Hope this helps.