Move code around to be better.. Don't read_frame unless we actually need to send_packet

Author: connortechnology

src/zm_ffmpeg_input.cpp

@@ -98,10 +98,13 @@ int FFmpeg_Input::Open(const char *filepath) {
 
       streams[i].context = avcodec_alloc_context3(streams[i].codec);
       avcodec_parameters_to_context(streams[i].context, input_format_context->streams[i]->codecpar);
+
       if (setup_hwaccel(streams[i].context,
-            chosen_codec_data, hw_device_ctx, "", input_format_context->streams[i]->codecpar->width,
+            chosen_codec_data, hw_device_ctx, "",
+            input_format_context->streams[i]->codecpar->width,
             input_format_context->streams[i]->codecpar->height
             )) {
+        Warning("Failed to setup hw_accel");
         continue;
       }
 
@@ -111,14 +114,16 @@ int FFmpeg_Input::Open(const char *filepath) {
       if (error < 0) {
         Error("Could not open input codec (error '%s')",
             av_make_error_string(error).c_str());
-        avcodec_free_context(&streams[i].context);
+
+        avcodec_free_context(&(streams[i].context));
         streams[i].context = nullptr;
         continue;
       }
       break;
     } // end foreach codec_data
 
     if (!streams[i].context) {
+      Debug(1, "Failed with known codecs, trying harder");
       if ((streams[i].codec = avcodec_find_decoder(input_format_context->streams[i]->codecpar->codec_id))) {
         Debug(1, "Using codec (%s) for stream %d", streams[i].codec->name, i);
         streams[i].context = avcodec_alloc_context3(streams[i].codec);
@@ -189,41 +194,18 @@ AVFrame *FFmpeg_Input::get_frame(int stream_id) {
     return nullptr;
   }
 
-  while (!frameComplete) {
-    int ret = av_read_frame(input_format_context, packet.get());
-    if (ret < 0) {
-      if (
-        // Check if EOF.
-        (ret == AVERROR_EOF || (input_format_context->pb && input_format_context->pb->eof_reached)) ||
-        // Check for Connection failure.
-        (ret == -110)
-      ) {
-        Info("av_read_frame returned %s.", av_make_error_string(ret).c_str());
-        return nullptr;
-      }
-      Error("Unable to read packet from stream %d: error %d \"%s\".",
-            packet->stream_index, ret, av_make_error_string(ret).c_str());
-      return nullptr;
-    }
-    ZM_DUMP_STREAM_PACKET(input_format_context->streams[packet->stream_index], packet, "Received packet");
-
-    //av_packet_guard pkt_guard{packet};
-
-    if ((stream_id >= 0) && (packet->stream_index != stream_id)) {
-      Debug(4, "Packet is not for our stream (%d)", packet->stream_index );
-      continue;
-    }
+  AVCodecContext *context = streams[stream_id].context;
 
-    AVCodecContext *context = streams[packet->stream_index].context;
+  while (!frameComplete) {
 
     frame = av_frame_ptr{zm_av_frame_alloc()};
     if (!frame) {
       Error("Unable to allocate frame.");
       return nullptr;
     }
-  
+
     // Since technically sending a packet can result in multiple frames (or buffered_frames) try receive_frame first.
-    ret = avcodec_receive_frame(context, frame.get());
+    int ret = avcodec_receive_frame(context, frame.get());
     Debug(1, "Ret from receive_frame ret: %d %s", ret, av_make_error_string(ret).c_str());
     if (ret == AVERROR(EAGAIN)) {
       // Perfectly normal
@@ -240,6 +222,30 @@ AVFrame *FFmpeg_Input::get_frame(int stream_id) {
       break;
     }
 
+    ret = av_read_frame(input_format_context, packet.get());
+    if (ret < 0) {
+      if (
+        // Check if EOF.
+        (ret == AVERROR_EOF || (input_format_context->pb && input_format_context->pb->eof_reached)) ||
+        // Check for Connection failure.
+        (ret == -110)
+      ) {
+        Info("av_read_frame returned %s.", av_make_error_string(ret).c_str());
+        return nullptr;
+      }
+      Error("Unable to read packet from stream %d: error %d \"%s\".",
+            packet->stream_index, ret, av_make_error_string(ret).c_str());
+      return nullptr;
+    }
+    ZM_DUMP_STREAM_PACKET(input_format_context->streams[packet->stream_index], packet, "Received packet");
+
+    //av_packet_guard pkt_guard{packet};
+
+    if ((stream_id >= 0) && (packet->stream_index != stream_id)) {
+      Debug(4, "Packet is not for our stream (%d)", packet->stream_index );
+      continue;
+    }
+
     ret = avcodec_send_packet(context, packet.get());
     if (ret == AVERROR(EAGAIN)) {
       Debug(2, "Unable to send packet %d %s", ret, av_make_error_string(ret).c_str());