Add extraction of fields according to source scan type

src/encmain.c

@@ -169,27 +169,42 @@ int main(int argc, char *argv[])
     uint32_t frames_done = 0;
     double psnr_sum[3] = { 0.0, 0.0, 0.0 };
 
+    int8_t field_parity = 0;
+    kvz_picture *frame_in = NULL;
+
     for (;;) {
+
       kvz_picture *img_in = NULL;
-      if (!feof(input) && (opts->frames == 0 || frames_read < opts->frames)) {
+
+      if (!feof(input) && (opts->frames == 0 || frames_read < opts->frames || field_parity == 1) ) {
         // Try to read an input frame.
-        img_in = api->picture_alloc(encoder->in.width, encoder->in.height);
-        if (!img_in) {
+        if(field_parity == 0) frame_in = api->picture_alloc(opts->config->width, opts->config->height);
+        if (!frame_in) {
           fprintf(stderr, "Failed to allocate image.\n");
           goto exit_failure;
         }
 
-        if (yuv_io_read(input, opts->config->width, opts->config->height, img_in)) {
-          frames_read += 1;
-        } else {
-          // EOF or some error
-          api->picture_free(img_in);
-          img_in = NULL;
-          if (!feof(input)) {
-            fprintf(stderr, "Failed to read a frame %d\n", frames_read);
-            goto exit_failure;
+        if (field_parity == 0){
+          if (yuv_io_read(input, opts->config->width, opts->config->height, frame_in)) {
+            frames_read += 1;
+            img_in = frame_in;
+          } else {
+            // EOF or some error
+            api->picture_free(img_in);
+            img_in = NULL;
+            if (!feof(input)) {
+              fprintf(stderr, "Failed to read a frame %d\n", frames_read);
+              goto exit_failure;
+            }
           }
         }
+
+        if (encoder->cfg->source_scan_type != 0){
+          img_in = api->picture_alloc(encoder->in.width, encoder->in.height);
+          yuv_io_extract_field(frame_in, encoder->cfg->source_scan_type, field_parity, img_in);
+          if (field_parity == 1) api->picture_free(frame_in);
+          field_parity ^= 1; //0->1 or 1->0
+        }
       }
 
       kvz_data_chunk* chunks_out = NULL;

src/encoder.c

@@ -474,8 +474,11 @@ void encoder_control_free(encoder_control_t *const encoder) {
 }
 
 void encoder_control_input_init(encoder_control_t * const encoder,
-                        const int32_t width, const int32_t height)
+                        const int32_t width, int32_t height)
 {
+  // Halve for interlaced content
+  if (encoder->in.source_scan_type != 0) height /= 2;
+
   encoder->in.width = width;
   encoder->in.height = height;
   encoder->in.real_width = width;

src/yuv_io.c

@@ -203,3 +203,44 @@ int yuv_io_write(FILE* file,
 
   return 1;
 }
+
+/**
+* \brief Separate a single field from a frame.
+*
+* \param frame_in           input frame to extract field from
+* \param source_scan_type   scan type of input material (0: progressive, 1:top field first, 2:bottom field first)
+* \param field parity   
+* \param field_out
+*
+* \return              1 on success, 0 on failure
+*/
+int yuv_io_extract_field(const kvz_picture *frame_in, unsigned source_scan_type, unsigned field_parity, kvz_picture *field_out)
+{
+  if ((source_scan_type != 1) && (source_scan_type != 2)) return 0;
+  if ((field_parity != 0)     && (field_parity != 1))     return 0;
+
+  unsigned offset = 0;
+  if (source_scan_type == 2) offset = frame_in->stride;
+
+  //Luma
+  for (int i = 0; i < field_out->height; ++i){
+    kvz_pixel *row_in  = frame_in->y + CLIP(0, frame_in->height - 1, 2 * i) * frame_in->stride + offset;
+    kvz_pixel *row_out = field_out->y + i * field_out->stride + offset;
+    memcpy(row_out, row_in, sizeof(kvz_pixel) * frame_in->width);
+  }
+
+  //Chroma
+  for (int i = 0; i < field_out->height / 2; ++i){
+    kvz_pixel *row_in = frame_in->u + CLIP(0, frame_in->height / 2 - 1, 2 * i) * frame_in->stride / 2 + offset / 2;
+    kvz_pixel *row_out = field_out->u + i * field_out->stride / 2 + offset / 2;
+    memcpy(row_out, row_in, sizeof(kvz_pixel) * frame_in->width / 2);
+  }
+
+  for (int i = 0; i < field_out->height / 2; ++i){
+    kvz_pixel *row_in = frame_in->v + CLIP(0, frame_in->height / 2 - 1, 2 * i) * frame_in->stride / 2 + offset / 2;
+    kvz_pixel *row_out = field_out->v + i * field_out->stride / 2 + offset / 2;
+    memcpy(row_out, row_in, sizeof(kvz_pixel) * frame_in->width / 2);
+  }
+
+  return 1;
+}

src/yuv_io.h

@@ -39,4 +39,6 @@ int yuv_io_write(FILE* file,
                 const kvz_picture *img,
                 unsigned output_width, unsigned output_height);
 
+int yuv_io_extract_field(const kvz_picture *frame_in, unsigned source_scan_type, unsigned field_parity, kvz_picture *field_out);
+
 #endif // YUV_IO_H_