关于处理视频断流的一些思考

虽然大部分摄像头都不支持热拔插，但我觉得思考一下相关问题还是有意义的。

先说结论：处理断流的根本在于同步信号。

正所谓，输入端通常会有同步头、同步行之类的时间串口，通过对这个期间的信号做处理以后使用其上升沿作为标志，用来重置存储地址和FIFO是处理输入同步的有效方法。

代码：

    //W Sync Port
    //wrclk
    reg                               r1_pre_vs        ;
    wire                              Pose_pre_vs      ;
    wire                              Nege_pre_vs      ;
    wire                              Ext_Pose_pre_vs  ;
    //sysclk
    reg                               sys_pre_vs       ;
    reg                               r1_sys_pre_vs    ;
    reg                               sys_Pose_pre_vs  ;
    reg                               sys_Nege_pre_vs  ;
    reg                               r_sys_Nege_pre_vs;
    reg  [1:0]                        wr_index         ;
    reg   [C_M_AXI_ADDR_WIDTH-1 : 0]  wr_base_addr     ;
    
    always @(posedge I_Pre_clk) begin
        r1_pre_vs <= I_Pre_vs;
    end

    assign  Pose_pre_vs = (I_Pre_vs == 1'b1)&&(r1_pre_vs == 1'b0);
    assign  Nege_pre_vs = (I_Pre_vs == 1'b0)&&(r1_pre_vs == 1'b1);

    always@(posedge M_AXI_ACLK) begin
        sys_pre_vs        <= I_Pre_vs  ;
        r1_sys_pre_vs     <= sys_pre_vs;
        r_sys_Nege_pre_vs <= sys_Nege_pre_vs;
    end

    always @(posedge M_AXI_ACLK) begin
        if(M_AXI_ARESETN == 1'b0) begin
            sys_Pose_pre_vs <= 1'b0;
            sys_Nege_pre_vs <= 1'b0;
        end else if(sys_pre_vs==1'b1&&r1_sys_pre_vs==1'b0) begin
            sys_Pose_pre_vs <= 1'b1;
            sys_Nege_pre_vs <= 1'b0; 
        end else if(sys_pre_vs==1'b0&&r1_sys_pre_vs==1'b1) begin
            sys_Pose_pre_vs <= 1'b0;
            sys_Nege_pre_vs <= 1'b1; 
        end else begin
            sys_Pose_pre_vs <= 1'b0;
            sys_Nege_pre_vs <= 1'b0;
        end
    end


    Data_sync_ext Data_sync_ext_Inst0(
        .clka           ( I_Pre_clk          ),
        .rst_n          ( M_AXI_ARESETN      ),    
        .pulse_a        ( Pose_pre_vs        ),
        .ext_pulse_a    ( Ext_Pose_pre_vs    )
    );

    always@(posedge M_AXI_ACLK)
        if(M_AXI_ARESETN == 1'b0) begin
            wr_index <= 'd1;
        end else if(sys_Nege_pre_vs == 1'b1&&wr_index == AXI_Buff_NUM) begin
            wr_index <= 'd1;
        end else if(sys_Nege_pre_vs==1'b1) begin
            wr_index <= wr_index + 1'b1;
        end else begin
            wr_index <= wr_index;
        end

        assign  O_wr_index = wr_index;
            
    always@(posedge M_AXI_ACLK)
        if(M_AXI_ARESETN == 1'b0) begin
            wr_base_addr <= 0;
        end    else if(sys_Nege_pre_vs == 1'b1&&wr_index == AXI_Buff_NUM) begin
            wr_base_addr <= 0;
        end else if(sys_Nege_pre_vs == 1'b1) begin
            wr_base_addr <= wr_base_addr + Total_Frame_Offset;
        end else begin
            wr_base_addr <= wr_base_addr;
        end

而处理输出就比较简单了，因为是你自己定义的，自己生成或使用现有的VGA或其他接口的同步帧即可。

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2024.04.03

在以太网传输的过程中处理断流数据这个思路非常好用；

这是因为UDP传输虽然快捷但是丢包的出现非常频繁。