fix to accept videos with different sample aspect ratio

src/ngx_http_video_thumbextractor_module_utils.c

@@ -386,15 +386,28 @@ ngx_http_video_thumbextractor_jpeg_memory_dest (j_compress_ptr cinfo, caddr_t *o
 }
 
 
+float display_aspect_ratio(AVCodecContext *pCodecCtx)
+{
+    double aspect_ratio = av_q2d(pCodecCtx->sample_aspect_ratio);
+    return ((float) pCodecCtx->width / pCodecCtx->height) * (aspect_ratio ? aspect_ratio : 1);
+}
+
+
+int display_width(AVCodecContext *pCodecCtx)
+{
+    return pCodecCtx->height * display_aspect_ratio(pCodecCtx);
+}
+
+
 int setup_parameters(ngx_http_video_thumbextractor_loc_conf_t *cf, ngx_http_video_thumbextractor_ctx_t *ctx, AVFormatContext *pFormatCtx, AVCodecContext *pCodecCtx)
 {
     if (ctx->height == 0) {
         // keep original format
-        ctx->width = pCodecCtx->width;
+        ctx->width = display_width(pCodecCtx);
         ctx->height = pCodecCtx->height;
     } else if (ctx->width == 0) {
         // calculate width related with original aspect
-        ctx->width = ctx->height * pCodecCtx->width / pCodecCtx->height;
+        ctx->width = ctx->height * display_aspect_ratio(pCodecCtx);
     }
 
     ctx->tile_sample_interval = cf->tile_sample_interval;
@@ -444,18 +457,18 @@ int setup_filters(ngx_http_video_thumbextractor_loc_conf_t *cf, ngx_http_video_t
     float            scale = 0.0, new_scale = 0.0, scale_sws = 0.0, scale_w = 0.0, scale_h = 0.0;
     int              sws_width = 0, sws_height = 0;
 
-    scale     = (float) pCodecCtx->width / pCodecCtx->height;
+    scale     = display_aspect_ratio(pCodecCtx);
     new_scale = (float) width / height;
 
     sws_width = width;
     sws_height = height;
 
     if (scale != new_scale) {
-        scale_w = (float) width / pCodecCtx->width;
+        scale_w = (float) width / display_width(pCodecCtx);
         scale_h = (float) height / pCodecCtx->height;
         scale_sws = (scale_w > scale_h) ? scale_w : scale_h;
 
-        sws_width = pCodecCtx->width * scale_sws + 0.5;
+        sws_width = display_width(pCodecCtx) * scale_sws + 0.5;
         sws_height = pCodecCtx->height * scale_sws + 0.5;
 
         needs_crop = 1;

test/video_thumbextractor_spec.rb

@@ -39,6 +39,24 @@
       end
     end
 
+    context "when the video has sample aspect ratio less than 1" do
+      it "should use the display dimensions as true dimensions" do
+        nginx_run_server(only_keyframe: 'off') do
+          content = image('/test_video_aspect_lt_1.mp4?second=2&height=90', {}, "200")
+          expect(content).to eq(IO.binread('test_video_aspect_lt_1.jpg'))
+        end
+      end
+    end
+
+    context "when the video has sample aspect ratio greater than 1" do
+      it "should use the display dimensions as true dimensions" do
+        nginx_run_server(only_keyframe: 'off') do
+          content = image('/test_video_aspect_gt_1.mp4?second=2&height=90', {}, "200")
+          expect(content).to eq(IO.binread('test_video_aspect_gt_1.jpg'))
+        end
+      end
+    end
+
     context "when the requested second is on the end of the video" do
       context "and using only_keyframe with previous time" do
         it "should return a 200" do