feat: flush frames when EOF encountered

src/ffmpeg.cr

@@ -36,4 +36,14 @@ module FFmpeg
     return "unknown" if success < 0
     String.new(buffer.to_unsafe) # unsafe as it's \0 terminated
   end
+
+  def self.mktag(a : Char, b : Char, c : Char, d : Char)
+    (a.ord) | (b.ord << 8) | (c.ord << 16) | (d.ord.to_u << 24)
+  end
+
+  def self.fferrtag(a : Char, b : Char, c : Char, d : Char)
+    -(mktag(a, b, c, d))
+  end
+
+  AVERROR_EOF = fferrtag('E', 'O', 'F', ' ')
 end

src/ffmpeg/codec.cr

@@ -63,8 +63,13 @@ class FFmpeg::Codec
 
   getter frame : Frame { Frame.new }
 
-  def decode(packet : Packet, &)
-    success = LibAV::Codec.send_packet(@context, packet)
+  def decode(packet : Packet?, &)
+    success = if packet
+                LibAV::Codec.send_packet(@context, packet)
+              else
+                # flush the codec for any final frames
+                LibAV::Codec.send_packet(@context, Pointer(FFmpeg::LibAV::Codec::Packet).null)
+              end
     raise "failed to read packet with #{success}: #{FFmpeg.get_error_message(success)}" if success < 0
 
     loop do

src/ffmpeg/format.cr

@@ -118,7 +118,15 @@ class FFmpeg::Format
 
   def read(&)
     status = LibAV::Format.read_frame(@context, packet)
-    raise "failed to read a frame with #{status}: #{FFmpeg.get_error_message(status)}" if status < 0
+
+    if status < 0
+      case status
+      when AVERROR_EOF
+        raise IO::EOFError.new(FFmpeg.get_error_message(status))
+      else
+        raise "failed to read a frame with #{status}: #{FFmpeg.get_error_message(status)}"
+      end
+    end
 
     begin
       yield packet

src/ffmpeg/video.cr

@@ -69,15 +69,21 @@ abstract class FFmpeg::Video
 
     seek(0, SeekStyle::Frame)
 
-    Log.trace { "extracting frames" }
-    while !closed?
-      format.read do |packet|
-        if packet.stream_index == stream_index
-          codec.decode(packet) do |frame|
-            yield frame
+    begin
+      Log.trace { "extracting frames" }
+      while !closed?
+        format.read do |packet|
+          if packet.stream_index == stream_index
+            codec.decode(packet) do |frame|
+              yield frame
+            end
           end
         end
       end
+    rescue error : IO::EOFError
+      codec.decode(nil) do |frame|
+        yield frame
+      end
     end
   ensure
     close