From 7854c0ad7381382e969d3ee92b3395a070e06e06 Mon Sep 17 00:00:00 2001
From: Alf <alf.g.jr@gmail.com>
Date: Tue, 22 Dec 2020 22:33:39 -0800
Subject: [PATCH] Use gop size for perPage results. #3

---
 src/ffprobe-wasm-wrapper.cpp  | 18 +++++++++++++++---
 www/src/components/File.vue   | 14 ++++++--------
 www/src/components/Frames.vue |  8 +++++++-
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/src/ffprobe-wasm-wrapper.cpp b/src/ffprobe-wasm-wrapper.cpp
index c27fea1..af7672f 100644
--- a/src/ffprobe-wasm-wrapper.cpp
+++ b/src/ffprobe-wasm-wrapper.cpp
@@ -64,6 +64,7 @@ typedef struct FileInfoResponse {
 typedef struct FramesResponse {
   std::vector<Frame> frames;
   int nb_frames;
+  int gop_size;
 } FramesResponse;
 
 FileInfoResponse get_file_info(std::string filename) {
@@ -200,8 +201,10 @@ FramesResponse get_frames(std::string filename, int offset) {
     AVPacket *pPacket = av_packet_alloc();
     AVFrame *pFrame = av_frame_alloc();
 
-    int how_many_packets_to_process = 48; // per page.
-    int frame_count = 1;
+    int max_packets_to_process = 1000;
+    int frame_count = 0;
+    int key_frames = 0;
+    int gop_size = 0;
 
     // Read video frames.
     while (av_read_frame(pFormatContext, pPacket) >= 0) {
@@ -217,6 +220,12 @@ FramesResponse get_frames(std::string filename, int offset) {
               continue;
             }
 
+            // Track keyframes so we paginate by each GOP.
+            if (pFrame->key_frame == 1) key_frames++;
+
+            // Break at the next keyframe found.
+            if (key_frames > 1) break;
+
             Frame f = {
               .frame_number = frame_count,
               .pict_type = (char) av_get_picture_type_char(pFrame->pict_type),
@@ -226,7 +235,7 @@ FramesResponse get_frames(std::string filename, int offset) {
             };
             r.frames.push_back(f);
 
-            if (--how_many_packets_to_process <= 0) break;
+            if (--max_packets_to_process <= 0) break;
           }
         }
         frame_count++;
@@ -237,6 +246,8 @@ FramesResponse get_frames(std::string filename, int offset) {
     av_packet_free(&pPacket);
     av_frame_free(&pFrame);
     avcodec_free_context(&pCodecContext);
+
+    r.gop_size = frame_count - offset;
     return r;
 }
 
@@ -287,6 +298,7 @@ EMSCRIPTEN_BINDINGS(structs) {
   emscripten::value_object<FramesResponse>("FramesResponse")
   .field("frames", &FramesResponse::frames)
   .field("nb_frames", &FramesResponse::nb_frames)
+  .field("gop_size", &FramesResponse::gop_size)
   ;
   function("get_frames", &get_frames);
 }
\ No newline at end of file
diff --git a/www/src/components/File.vue b/www/src/components/File.vue
index a039411..c6fbbd7 100644
--- a/www/src/components/File.vue
+++ b/www/src/components/File.vue
@@ -15,7 +15,7 @@
         <div v-if="info">
           <div class="mt-3">Selected file: {{ file ? `${file.name}: ${file.size} bytes` : '' }}</div>
 
-          <b-tabs class="mt-4">
+          <b-tabs class="mt-4" v-model="tabIndex">
             <b-tab title="Overview" class="mt-2">
               <div v-if="info">
                 <Overview :info="info" />
@@ -42,18 +42,16 @@ export default {
   data() {
     return {
       file: null,
-      data: null,
       info: null,
-    }
-  },
-  created() {
-    this.$worker.onmessage = (e) => {
-      this.info = e.data;
+      tabIndex: 0,
     }
   },
   methods: {
     onFile(event) {
-      this.data = null;
+      this.tabIndex = 0;
+      this.$worker.onmessage = (e) => {
+        this.info = e.data;
+      }
       const file = event.dataTransfer ? event.dataTransfer.files[0] : event.target.files[0];
       this.$worker.postMessage([ 'get_file_info', file ]);
     }
diff --git a/www/src/components/Frames.vue b/www/src/components/Frames.vue
index 7380f9a..e6f2104 100644
--- a/www/src/components/Frames.vue
+++ b/www/src/components/Frames.vue
@@ -3,6 +3,7 @@
     <h4>Frames</h4>
     <div v-if="!data">Loading...</div>
     <div v-if="data">
+      <p class="float-left">GOP Size: {{ data.gop_size }}</p>
       <p class="text-right">Total: {{ data.nb_frames }}</p>
 
       <b-pagination
@@ -19,6 +20,9 @@
             <b-spinner class="align-middle"></b-spinner>
           </div>
         </template>
+        <template #cell(frame_number)="data">
+          {{ data.value + 1 }}
+        </template>
         <template #cell(pict_type)="data">
           {{ String.fromCharCode(data.value) }}
         </template>
@@ -43,11 +47,13 @@ export default {
     return {
       data: null,
       currentPage: 1,
-      perPage: 48,
       isBusy: false,
     };
   },
   computed: {
+    perPage() {
+      return this.data.gop_size;
+    },
     pages() {
       return this.data.nb_frames;
     },