ESP-WHO（一）ESP32 摄像头驱动分析

其他 2019-03-14 16:53:05 阅读次数: 0
版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq_27114397/article/details/86369437

ESP-WHO（一）ESP32 摄像头驱动分析

ESP32 摄像头驱动分析

摄像头代码

摄像头初始化

Step:

  1. 寻找摄像头
    1. 提供摄像头时钟、初始化 SCCB 总线、硬件复位摄像头
    2. 轮询地址寻找摄像头，通过 SCCB 总线读取摄像头 ID 等信息
    3. 更改摄像头的 ID 判断型号，并绑定对应的相关函数（摄像头传感器配置相关函数）
  2. 初始化摄像头
    1. 根据选择的图像格式、和是否是高速模式，选择对应的 DMA BUF 处理函数和 DMA FIFO 模式
    2. 初始化 I2S 总线，使能 I2S_IN_DONE_INT 中断：当前 DMA 接收链表描述符被处理时即触发此中断 3. 初始化 DMA 相关变量（链表描述符、DMA 使用的数据缓冲区链表等），DMA 单次最多 4KB 、每行 DMA 采集几次
    3. 初始化存储图像的数据缓冲区（添加到一个链表中）并清空
    4. 初始化相关信号量：DMA 数据采集完成、一帧图像采集完成信号量、图像数据缓冲区进出信号量
    5. 创建 dma_filter_task 将 DMA 数据转换成像素数据并存储到图像缓冲区，这里也会检查是否有脏数据产生，判断是否接收完一帧完整的图像
    6. 初始化 vsync io 中断：每一帧图像开始结尾都会发生电平翻转
    7. 摄像头传感器相关配置（图像大小、格式等）

函数说明：

  1. esp_camera_init 函数：
    1. 寻找摄像头
    2. 摄像头相关初始化
esp_err_t esp_camera_init(const camera_config_t* config)
{
    camera_model_t camera_model = CAMERA_NONE;
    esp_err_t err = camera_probe(config, &camera_model);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Camera probe failed with error 0x%x", err);
        goto fail;
    }
    err = camera_init(config);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Camera init failed with error 0x%x", err);
        return err;
    }
    return ESP_OK;

fail:
    free(s_state);
    s_state = NULL;
    camera_disable_out_clock();
    return err;
}

函数说明：

  1. camera_probe 函数：
    1. 摄像头时钟配置、SCCB 总线初始化、硬件复位摄像头
    2. 轮询 127 以内的地址进行寻找摄像头、读取基本信息 PID、VER、MIDL、MIDH
    3. 根据摄像头 PID 判断设备类型，并绑定相应的函数、软件复位摄像头
esp_err_t camera_probe(const camera_config_t* config, camera_model_t* out_camera_model)
{
    if (s_state != NULL) {
        return ESP_ERR_INVALID_STATE;
    }

    s_state = (camera_state_t*) calloc(sizeof(*s_state), 1);
    if (!s_state) {
        return ESP_ERR_NO_MEM;
    }

    ESP_LOGD(TAG, "Enabling XCLK output");
    camera_enable_out_clock(config);

    ESP_LOGD(TAG, "Initializing SSCB");
    SCCB_Init(config->pin_sscb_sda, config->pin_sscb_scl);
	
    if(config->pin_pwdn >= 0) {
        ESP_LOGD(TAG, "Resetting camera by power down line");
        gpio_config_t conf = { 0 };
        conf.pin_bit_mask = 1LL << config->pin_pwdn;
        conf.mode = GPIO_MODE_OUTPUT;
        gpio_config(&conf);

        // carefull, logic is inverted compared to reset pin
        gpio_set_level(config->pin_pwdn, 1);
        vTaskDelay(10 / portTICK_PERIOD_MS);
        gpio_set_level(config->pin_pwdn, 0);
        vTaskDelay(10 / portTICK_PERIOD_MS);
    }

    if(config->pin_reset >= 0) {
        ESP_LOGD(TAG, "Resetting camera");
        gpio_config_t conf = { 0 };
        conf.pin_bit_mask = 1LL << config->pin_reset;
        conf.mode = GPIO_MODE_OUTPUT;
        gpio_config(&conf);

        gpio_set_level(config->pin_reset, 0);
        vTaskDelay(10 / portTICK_PERIOD_MS);
        gpio_set_level(config->pin_reset, 1);
        vTaskDelay(10 / portTICK_PERIOD_MS);
#if CONFIG_OV2640_SUPPORT
    } else {
        //reset OV2640
        SCCB_Write(0x30, 0xFF, 0x01);//bank sensor
        SCCB_Write(0x30, 0x12, 0x80);//reset
        vTaskDelay(10 / portTICK_PERIOD_MS);
#endif
    }

    ESP_LOGD(TAG, "Searching for camera address");
    vTaskDelay(10 / portTICK_PERIOD_MS);
    uint8_t slv_addr = SCCB_Probe();
    if (slv_addr == 0) {
        *out_camera_model = CAMERA_NONE;
        camera_disable_out_clock();
        return ESP_ERR_CAMERA_NOT_DETECTED;
    }
    s_state->sensor.slv_addr = slv_addr;

    //s_state->sensor.slv_addr = 0x30;
    ESP_LOGD(TAG, "Detected camera at address=0x%02x", s_state->sensor.slv_addr);
    sensor_id_t* id = &s_state->sensor.id;

    id->PID = SCCB_Read(s_state->sensor.slv_addr, REG_PID);
    id->VER = SCCB_Read(s_state->sensor.slv_addr, REG_VER);
    id->MIDL = SCCB_Read(s_state->sensor.slv_addr, REG_MIDL);
    id->MIDH = SCCB_Read(s_state->sensor.slv_addr, REG_MIDH);
    vTaskDelay(10 / portTICK_PERIOD_MS);
    ESP_LOGD(TAG, "Camera PID=0x%02x VER=0x%02x MIDL=0x%02x MIDH=0x%02x",
             id->PID, id->VER, id->MIDH, id->MIDL);

    switch (id->PID) {
#if CONFIG_OV2640_SUPPORT
    case OV2640_PID:
        *out_camera_model = CAMERA_OV2640;
        ov2640_init(&s_state->sensor);
        break;
#endif
#if CONFIG_OV7725_SUPPORT
    case OV7725_PID:
        *out_camera_model = CAMERA_OV7725;
        ov7725_init(&s_state->sensor);
        break;
#endif
    default:
        id->PID = 0;
        *out_camera_model = CAMERA_UNKNOWN;
        camera_disable_out_clock();
        ESP_LOGE(TAG, "Detected camera not supported.");
        return ESP_ERR_CAMERA_NOT_SUPPORTED;
    }

    ESP_LOGD(TAG, "Doing SW reset of sensor");
    s_state->sensor.reset(&s_state->sensor);

    return ESP_OK;
}

函数说明：

  1. camera_init 函数：
    1. 根据选择的图像格式、和是否是高速模式，选择对应的 DMA BUF 处理函数和 DMA FIFO 模式
    2. 初始化 I2S 总线，相关引脚配置并使能 I2S_IN_DONE_INT 中断：当前 DMA 接收链表描述符被处理时即触发此中断 3. 初始化 DMA 相关变量（链表描述符、DMA 使用的数据缓冲区链表等），DMA 单次最多 4KB 、每行 DMA 采集几次
    3. 初始化存储图像的数据缓冲区（添加到一个链表中）并清空
    4. 初始化相关信号量：DMA 数据采集完成、一帧图像采集完成信号量、图像数据缓冲区进出信号量
    5. 创建 dma_filter_task 将 DMA 数据转换成像素数据并存储到图像缓冲区，这里也会检查是否有脏数据产生，判断是否接收完一帧完整的图像
    6. 初始化 vsync io 中断：每一帧图像开始结尾都会发生电平翻转
    7. 摄像头传感器相关配置（图像大小、格式等）
    8. 跳过前面几帧数据
esp_err_t camera_init(const camera_config_t* config)
{
    if (!s_state) {
        return ESP_ERR_INVALID_STATE;
    }
    if (s_state->sensor.id.PID == 0) {
        return ESP_ERR_CAMERA_NOT_SUPPORTED;
    }
    memcpy(&s_state->config, config, sizeof(*config));
    esp_err_t err = ESP_OK;
    framesize_t frame_size = (framesize_t) config->frame_size;
    pixformat_t pix_format = (pixformat_t) config->pixel_format;
    s_state->width = resolution[frame_size][0];
    s_state->height = resolution[frame_size][1];

    if (pix_format == PIXFORMAT_GRAYSCALE) {
        s_state->fb_size = s_state->width * s_state->height;
        if (is_hs_mode()) {
            s_state->sampling_mode = SM_0A00_0B00;
            s_state->dma_filter = &dma_filter_grayscale_highspeed;
        } else {
            s_state->sampling_mode = SM_0A0B_0C0D;
            s_state->dma_filter = &dma_filter_grayscale;
        }
        s_state->in_bytes_per_pixel = 2;       // camera sends YUYV
        s_state->fb_bytes_per_pixel = 1;       // frame buffer stores Y8
    } else if (pix_format == PIXFORMAT_YUV422 || pix_format == PIXFORMAT_RGB565) {
        s_state->fb_size = s_state->width * s_state->height * 2;
        if (is_hs_mode()) {
            s_state->sampling_mode = SM_0A00_0B00;
            s_state->dma_filter = &dma_filter_yuyv_highspeed;
        } else {
            s_state->sampling_mode = SM_0A0B_0C0D;
            s_state->dma_filter = &dma_filter_yuyv;
        }
        s_state->in_bytes_per_pixel = 2;       // camera sends YUYV
        s_state->fb_bytes_per_pixel = 2;       // frame buffer stores Y8
    } else if (pix_format == PIXFORMAT_JPEG) {
        if (s_state->sensor.id.PID != OV2640_PID) {
            ESP_LOGE(TAG, "JPEG format is only supported for ov2640");
            err = ESP_ERR_NOT_SUPPORTED;
            goto fail;
        }
        int qp = config->jpeg_quality;
        int compression_ratio_bound = 1;
        if (qp > 10) {
            compression_ratio_bound = 16;
        } else if (qp > 5) {
            compression_ratio_bound = 10;
        } else {
            compression_ratio_bound = 4;
        }
        (*s_state->sensor.set_quality)(&s_state->sensor, qp);
        s_state->in_bytes_per_pixel = 2;
        s_state->fb_bytes_per_pixel = 2;
        s_state->fb_size = (s_state->width * s_state->height * s_state->fb_bytes_per_pixel) / compression_ratio_bound;
        s_state->dma_filter = &dma_filter_jpeg;
        s_state->sampling_mode = SM_0A00_0B00;
    } else {
        ESP_LOGE(TAG, "Requested format is not supported");
        err = ESP_ERR_NOT_SUPPORTED;
        goto fail;
    }

    ESP_LOGD(TAG, "in_bpp: %d, fb_bpp: %d, fb_size: %d, mode: %d, width: %d height: %d",
             s_state->in_bytes_per_pixel, s_state->fb_bytes_per_pixel,
             s_state->fb_size, s_state->sampling_mode,
             s_state->width, s_state->height);

    i2s_init();

    err = dma_desc_init();
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to initialize I2S and DMA");
        goto fail;
    }

    //s_state->fb_size = 75 * 1024;
    err = camera_fb_init(s_state->config.fb_count);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to allocate frame buffer");
        goto fail;
    }

    s_state->data_ready = xQueueCreate(16, sizeof(size_t));
    if (s_state->data_ready == NULL) {
        ESP_LOGE(TAG, "Failed to dma queue");
        err = ESP_ERR_NO_MEM;
        goto fail;
    }

    if(s_state->config.fb_count == 1) {
        s_state->frame_ready = xSemaphoreCreateBinary();
        if (s_state->frame_ready == NULL) {
            ESP_LOGE(TAG, "Failed to create semaphore");
            err = ESP_ERR_NO_MEM;
            goto fail;
        }
    } else {
        s_state->fb_in = xQueueCreate(s_state->config.fb_count, sizeof(camera_fb_t *));
        s_state->fb_out = xQueueCreate(1, sizeof(camera_fb_t *));
        if (s_state->fb_in == NULL || s_state->fb_out == NULL) {
            ESP_LOGE(TAG, "Failed to fb queues");
            err = ESP_ERR_NO_MEM;
            goto fail;
        }
    }

    //ToDo: core affinity?
    if (!xTaskCreatePinnedToCore(&dma_filter_task, "dma_filter", 4096, NULL, 10, &s_state->dma_filter_task, 1)) {
        ESP_LOGE(TAG, "Failed to create DMA filter task");
        err = ESP_ERR_NO_MEM;
        goto fail;
    }

    vsync_intr_disable();
    gpio_install_isr_service(ESP_INTR_FLAG_LEVEL1 | ESP_INTR_FLAG_IRAM);
    err = gpio_isr_handler_add(s_state->config.pin_vsync, &vsync_isr, NULL);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "vsync_isr_handler_add failed (%x)", err);
        goto fail;
    }

    s_state->sensor.status.framesize = frame_size;
    s_state->sensor.pixformat = pix_format;
    ESP_LOGD(TAG, "Setting frame size to %dx%d", s_state->width, s_state->height);
    if (s_state->sensor.set_framesize(&s_state->sensor, frame_size) != 0) {
        ESP_LOGE(TAG, "Failed to set frame size");
        err = ESP_ERR_CAMERA_FAILED_TO_SET_FRAME_SIZE;
        goto fail;
    }
    s_state->sensor.set_pixformat(&s_state->sensor, pix_format);

    if (s_state->sensor.id.PID == OV2640_PID) {
        s_state->sensor.set_gainceiling(&s_state->sensor, GAINCEILING_2X);
        s_state->sensor.set_bpc(&s_state->sensor, false);
        s_state->sensor.set_wpc(&s_state->sensor, true);
        s_state->sensor.set_lenc(&s_state->sensor, true);
    }

    skip_frame();
    //todo: for some reason the first set of the quality does not work.
    if (pix_format == PIXFORMAT_JPEG) {
        (*s_state->sensor.set_quality)(&s_state->sensor, config->jpeg_quality);
    }
    s_state->sensor.init_status(&s_state->sensor);
    return ESP_OK;

fail:
    esp_camera_deinit();
    return err;
}

数据采集

Step：

  1. DMA 链表描述符初始化，初始化 4 行图像数据大小的 buf 空间
  2. 开始接收数据时，先运行 i2s_run() ，等待 VSYNC 信号变为高时，即表示摄像头端已经开始一帧图像传输，需要跳过 VSYNC 为低时的数据，再采集过程中出现 VSYNC 由高到低变化，则表示一帧图像传输完成，VSYNC 中断服务函数 vsync_isr
  3. 当前 DMA 接收链表描述符被处理完成时将触发 I2S_IN_DONE_INT 中断，进入 i2s_isr()，中断服务函数中，首先清楚中断标志，之后通过 signal_dma_buf_received 函数发出一次 DMA 数据采集完成信号，若一帧图像数据接收完成就停止 i2s
  4. 在 dma_filter_task 任务中会等待 DMA 数据采集完成信号，并处理 DMA buffer 中的数据放入图像缓冲区中
  5. 循环 3、4 步骤直到一帧图像数据接收完全，发出帧接收完信号

函数说明：

  1. i2s_run 函数:
    1. 跳过当前这一帧（VSYNC 为高的这段数据丢掉），等待 VSYNC 为低，开始 i2s 接收数据
    2. 并在 i2s_start_bus 函数中使能 VSYNC 中断
static void i2s_run()
{
    for (int i = 0; i < s_state->dma_desc_count; ++i) {
        lldesc_t* d = &s_state->dma_desc[i];
        ESP_LOGV(TAG, "DMA desc %2d: %u %u %u %u %u %u %p %p",
                 i, d->length, d->size, d->offset, d->eof, d->sosf, d->owner, d->buf, d->qe.stqe_next);
        memset(s_state->dma_buf[i], 0, d->length);
    }

    // wait for frame
    camera_fb_int_t * fb = s_state->fb;
    while(s_state->config.fb_count > 1) {
        while(s_state->fb->ref && s_state->fb->next != fb) {
            s_state->fb = s_state->fb->next;
        }
        if(s_state->fb->ref == 0) {
            break;
        }
        vTaskDelay(2);
    }

    // wait for vsync
    ESP_LOGV(TAG, "Waiting for negative edge on VSYNC");
    while (_gpio_get_level(s_state->config.pin_vsync) != 0) {
        ;
    }
    ESP_LOGV(TAG, "Got VSYNC");

    i2s_start_bus();
}

static void IRAM_ATTR i2s_start_bus()
{
    s_state->dma_desc_cur = 0;
    s_state->dma_received_count = 0;
    //s_state->dma_filtered_count = 0;
    esp_intr_disable(s_state->i2s_intr_handle);
    i2s_conf_reset();

    I2S0.rx_eof_num = s_state->dma_sample_count;
    I2S0.in_link.addr = (uint32_t) &s_state->dma_desc[0];
    I2S0.in_link.start = 1;
    I2S0.int_clr.val = I2S0.int_raw.val;
    I2S0.int_ena.val = 0;
    I2S0.int_ena.in_done = 1;

    esp_intr_enable(s_state->i2s_intr_handle);
    I2S0.conf.rx_start = 1;
    if (s_state->config.pixel_format == PIXFORMAT_JPEG) {
        vsync_intr_enable();
    }
}

函数说明：

  1. dma_desc_init 函数：
    1. DMA 链表描述符初始化，初始化 4 行图像数据大小的 buf 空间
    2. 分配 DMA buf 空间
static esp_err_t dma_desc_init()
{
    assert(s_state->width % 4 == 0);
    size_t line_size = s_state->width * s_state->in_bytes_per_pixel *
                       i2s_bytes_per_sample(s_state->sampling_mode);
    ESP_LOGD(TAG, "Line width (for DMA): %d bytes", line_size);
    size_t dma_per_line = 1;
    size_t buf_size = line_size;
    while (buf_size >= 4096) {
        buf_size /= 2;
        dma_per_line *= 2;
    }
    size_t dma_desc_count = dma_per_line * 4;
    s_state->dma_buf_width = line_size;
    s_state->dma_per_line = dma_per_line;
    s_state->dma_desc_count = dma_desc_count;
    ESP_LOGD(TAG, "DMA buffer size: %d, DMA buffers per line: %d", buf_size, dma_per_line);
    ESP_LOGD(TAG, "DMA buffer count: %d", dma_desc_count);
    ESP_LOGD(TAG, "DMA buffer total: %d bytes", buf_size * dma_desc_count);

    s_state->dma_buf = (dma_elem_t**) malloc(sizeof(dma_elem_t*) * dma_desc_count);
    if (s_state->dma_buf == NULL) {
        return ESP_ERR_NO_MEM;
    }
    s_state->dma_desc = (lldesc_t*) malloc(sizeof(lldesc_t) * dma_desc_count);
    if (s_state->dma_desc == NULL) {
        return ESP_ERR_NO_MEM;
    }
    size_t dma_sample_count = 0;
    for (int i = 0; i < dma_desc_count; ++i) {
        ESP_LOGD(TAG, "Allocating DMA buffer #%d, size=%d", i, buf_size);
        dma_elem_t* buf = (dma_elem_t*) malloc(buf_size);
        if (buf == NULL) {
            return ESP_ERR_NO_MEM;
        }
        s_state->dma_buf[i] = buf;
        ESP_LOGV(TAG, "dma_buf[%d]=%p", i, buf);

        lldesc_t* pd = &s_state->dma_desc[i];
        pd->length = buf_size;
        if (s_state->sampling_mode == SM_0A0B_0B0C &&
                (i + 1) % dma_per_line == 0) {
            pd->length -= 4;
        }
        dma_sample_count += pd->length / 4;
        pd->size = pd->length;
        pd->owner = 1;
        pd->sosf = 1;
        pd->buf = (uint8_t*) buf;
        pd->offset = 0;
        pd->empty = 0;
        pd->eof = 1;
        pd->qe.stqe_next = &s_state->dma_desc[(i + 1) % dma_desc_count];
    }
    s_state->dma_sample_count = dma_sample_count;
    return ESP_OK;
}

函数说明：

  1. vsync_isr 函数：
    1. 当摄像头一帧数据发送完， VSYNC 由高变低触发中断
    2. 如果是多帧缓存的方式，将继续下一次采集
static void IRAM_ATTR vsync_isr(void* arg)
{
    GPIO.status1_w1tc.val = GPIO.status1.val;
    GPIO.status_w1tc = GPIO.status;
    bool need_yield = false;
    //if vsync is low and we have received some data, frame is done
    if (_gpio_get_level(s_state->config.pin_vsync) == 0) {
        if(s_state->dma_received_count > 0) {
            signal_dma_buf_received(&need_yield);
            //ets_printf("end_vsync\n");
            if(s_state->dma_filtered_count > 1 || s_state->config.fb_count > 1) {
                i2s_stop(&need_yield);
            }
        }
        if(s_state->config.fb_count > 1 || s_state->dma_filtered_count < 2) {
            I2S0.conf.rx_start = 0;
            I2S0.in_link.start = 0;
            I2S0.int_clr.val = I2S0.int_raw.val;
            i2s_conf_reset();
            s_state->dma_desc_cur = (s_state->dma_desc_cur + 1) % s_state->dma_desc_count;
            //I2S0.rx_eof_num = s_state->dma_sample_count;
            I2S0.in_link.addr = (uint32_t) &s_state->dma_desc[s_state->dma_desc_cur];
            I2S0.in_link.start = 1;
            I2S0.conf.rx_start = 1;
            s_state->dma_received_count = 0;
        }
    }
    if (need_yield) {
        portYIELD_FROM_ISR();
    }
}

函数说明：

  1. i2s_isr 函数：
    1. 当前 DMA 接收链表描述符被处理完成时将触发 I2S_IN_DONE_INT 中断，在中断服务函数中判断是否接收完成（非 JPEG 格式），并调用 signal_dma_buf_received 函数
static void IRAM_ATTR i2s_isr(void* arg)
{
    I2S0.int_clr.val = I2S0.int_raw.val;
    bool need_yield = false;
    signal_dma_buf_received(&need_yield);
    if (s_state->config.pixel_format != PIXFORMAT_JPEG
     && s_state->dma_received_count == s_state->height * s_state->dma_per_line) {
        i2s_stop(&need_yield);
    }
    if (need_yield) {
        portYIELD_FROM_ISR();
    }
}

函数说明：

  1. signal_dma_buf_received 函数：
    1. 发出 DMA 接收完成信号，给出当前处理的 DMA 链表描述符索引
static void IRAM_ATTR signal_dma_buf_received(bool* need_yield)
{
    size_t dma_desc_filled = s_state->dma_desc_cur;
    s_state->dma_desc_cur = (dma_desc_filled + 1) % s_state->dma_desc_count;
    s_state->dma_received_count++;
    if(!s_state->fb->ref && s_state->fb->bad){
        *need_yield = false;
        return;
    }
    BaseType_t higher_priority_task_woken;
    BaseType_t ret = xQueueSendFromISR(s_state->data_ready, &dma_desc_filled, &higher_priority_task_woken);
    if (ret != pdTRUE) {
        if(!s_state->fb->ref) {
            s_state->fb->bad = 1;
        }
        //ESP_EARLY_LOGW(TAG, "qsf:%d", s_state->dma_received_count);
        //ets_printf("qsf:%d\n", s_state->dma_received_count);
    }
    *need_yield = (ret == pdTRUE && higher_priority_task_woken == pdTRUE);
}

函数说明：

  1. dma_filter_task 函数：
    1. 接收 DMA 接收完成信号，判断是否为最后一次处理，是则调用 dma_finish_frame 函数，否则，调用 dma_filter_buffer 函数将 DMA BUF 中的数据放入图像数据缓冲区中
static void IRAM_ATTR dma_filter_task(void *pvParameters)
{
    s_state->dma_filtered_count = 0;
    while (true) {
        size_t buf_idx;
        if(xQueueReceive(s_state->data_ready, &buf_idx, portMAX_DELAY) == pdTRUE) {
            if (buf_idx == SIZE_MAX) {
                //this is the end of the frame
                dma_finish_frame();
            } else {
                dma_filter_buffer(buf_idx);
            }
        }
    }
}

函数说明：

  1. dma_finish_frame 函数：
    1. 如果是脏数据重新采集一次数据
static void IRAM_ATTR dma_finish_frame()
{
    size_t buf_len = s_state->width * s_state->fb_bytes_per_pixel / s_state->dma_per_line;

    if(!s_state->fb->ref) {
        // is the frame bad?
        if(s_state->fb->bad){
            s_state->fb->bad = 0;
            s_state->fb->len = 0;
            *((uint32_t *)s_state->fb->buf) = 0;
            if(s_state->config.fb_count == 1) {
                i2s_start_bus();
            }
        } else {
            s_state->fb->len = s_state->dma_filtered_count * buf_len;
            if(s_state->fb->len) {
                //find the end marker for JPEG. Data after that can be discarded
                if(s_state->fb->format == PIXFORMAT_JPEG){
                    uint8_t * dptr = &s_state->fb->buf[s_state->fb->len - 1];
                    while(dptr > s_state->fb->buf){
                        if(dptr[0] == 0xFF && dptr[1] == 0xD9 && dptr[2] == 0x00 && dptr[3] == 0x00){
                            dptr += 2;
                            s_state->fb->len = dptr - s_state->fb->buf;
                            if((s_state->fb->len & 0x1FF) == 0){
                                s_state->fb->len += 1;
                            }
                            if((s_state->fb->len % 100) == 0){
                                s_state->fb->len += 1;
                            }
                            break;
                        }
                        dptr--;
                    }
                }
                //send out the frame
                camera_fb_done();
            } else if(s_state->config.fb_count == 1){
                //frame was empty?
                i2s_start_bus();
            }
        }
    } else if(s_state->fb->len) {
        camera_fb_done();
    }
    s_state->dma_filtered_count = 0;
}

函数说明：

  1. dma_filter_buffer 函数：
    1. 调用 DMA BUF 处理函数，将数据转换（根据 DMA FIFO 模式）并放入图像数据缓冲区
    2. 通过检查第一次 DMA 采集的数据是否错误判断本次数据是否为脏数据
static void IRAM_ATTR dma_filter_buffer(size_t buf_idx)
{
    //no need to process the data if frame is in use or is bad
    if(s_state->fb->ref || s_state->fb->bad) {
        return;
    }

    //check if there is enough space in the frame buffer for the new data
    size_t buf_len = s_state->width * s_state->fb_bytes_per_pixel / s_state->dma_per_line;
    size_t fb_pos = s_state->dma_filtered_count * buf_len;
    if(fb_pos > s_state->fb_size - buf_len) {
        //size_t processed = s_state->dma_received_count * buf_len;
        //ets_printf("[%s:%u] ovf pos: %u, processed: %u\n", __FUNCTION__, __LINE__, fb_pos, processed);
        return;
    }

    //convert I2S DMA buffer to pixel data
    (*s_state->dma_filter)(s_state->dma_buf[buf_idx], &s_state->dma_desc[buf_idx], s_state->fb->buf + fb_pos);

    //first frame buffer
    if(!s_state->dma_filtered_count) {
        //check for correct JPEG header
        if(s_state->sensor.pixformat == PIXFORMAT_JPEG) {
            uint32_t sig = *((uint32_t *)s_state->fb->buf) & 0xFFFFFF;
            if(sig != 0xffd8ff) {
                //ets_printf("bad header\n");
                s_state->fb->bad = 1;
                return;
            }
        }
        //set the frame properties
        s_state->fb->width = resolution[s_state->sensor.status.framesize][0];
        s_state->fb->height = resolution[s_state->sensor.status.framesize][1];
        s_state->fb->format = s_state->sensor.pixformat;
    }
    s_state->dma_filtered_count++;
}

函数说明：

  1. camera_fb_done 函数：
    1. 帧缓存完成，若是单帧缓存模式，将给出帧已经接收完的信号
    2. 若是多帧缓存模式，将当前的这一帧放入到出队的队列中，在其放入入队的队列前将不可用以缓存图像数据
static void IRAM_ATTR camera_fb_done()
{
    camera_fb_int_t * fb = NULL, * fb2 = NULL;
    BaseType_t taskAwoken = 0;

    if(s_state->config.fb_count == 1) {
        xSemaphoreGive(s_state->frame_ready);
        return;
    }

    fb = s_state->fb;
    if(!fb->ref && fb->len) {
        //add reference
        fb->ref = 1;

        //check if the queue is full
        if(xQueueIsQueueFullFromISR(s_state->fb_out) == pdTRUE) {
            //pop frame buffer from the queue
            if(xQueueReceiveFromISR(s_state->fb_out, &fb2, &taskAwoken) == pdTRUE) {
                //free the popped buffer
                fb2->ref = 0;
                fb2->len = 0;
                //push the new frame to the end of the queue
                xQueueSendFromISR(s_state->fb_out, &fb, &taskAwoken);
            } else {
                //queue is full and we could not pop a frame from it
            }
        } else {
            //push the new frame to the end of the queue
            xQueueSendFromISR(s_state->fb_out, &fb, &taskAwoken);
        }
    } else {
        //frame was referenced or empty
    }

    //return buffers to be filled
    while(xQueueReceiveFromISR(s_state->fb_in, &fb2, &taskAwoken) == pdTRUE) {
        fb2->ref = 0;
        fb2->len = 0;
    }

    //advance frame buffer only if the current one has data
    if(s_state->fb->len) {
        s_state->fb = s_state->fb->next;
    }
    //try to find the next free frame buffer
    while(s_state->fb->ref && s_state->fb->next != fb) {
        s_state->fb = s_state->fb->next;
    }
    //is the found frame buffer free?
    if(!s_state->fb->ref) {
        //buffer found. make sure it's empty
        s_state->fb->len = 0;
        *((uint32_t *)s_state->fb->buf) = 0;
    } else {
        //stay at the previous buffer
        s_state->fb = fb;
    }
}

猜你喜欢

转载自blog.csdn.net/qq_27114397/article/details/86369437
今日推荐
TIOBE 5 月榜单：Fortran “复活”进入 Top 10
GCC 14.1 发布
面壁智能发布 Eurux-8x22B 开源大模型 —— 堪称「理科状元」
开源日报 | 谷歌扶持鸿蒙上位；开源Rabbit R1；Docker加持的安卓手机；微软的焦虑和野心；海尔电器把开放平台关了
中国码农的“35岁魔咒”
蘭雅 CorelDRAW 插件 2024.5.1 国际劳动节版，免费下载
Arc Browser for Windows 1.0 正式 GA
90后程序员开发视频搬运软件、不到一年获利超 700 万，结局很刑！
周排行
Java自定义时间格式
同步整形电路
在开发中最最最常用的字符串的属性大集合
Linux 查看端口占用并杀掉
Java基础四：ArrayList
多线程之死锁就是这么简单
mysql 基础命令集
awk 命令详解
Centos6.3编译安装nginx+php步骤
OCR （Optical Character Recognition，光学字符识别）
每日归档
更多
2024-05-08(42)
2024-05-07(14)
2024-05-06(40)
2024-05-05(0)
2024-05-04(7)
2024-05-03(19)
2024-05-02(0)
2024-05-01(4)
2024-04-30(1)
2024-04-29(40)

代码天地 © 2018 codetd.com

境外服务器   最新电视剧2022