Guess video bitrate if not provided by ffmpeg

The total bitrate may be given, but the video and/or audio
not. If the video bitrate is not available, attempt to use
the total bitrate

Author: brarcher

app/src/main/java/protect/videotranscoder/FFmpegUtil.java

@@ -208,6 +208,7 @@ public void onResult(String mediaDetailsStr)
     static MediaInfo parseMediaInfo(File mediaFile, String string)
     {
         long durationMs = 0;
+        Integer totalBitrate = null;
         MediaContainer container = null;
         VideoCodec videoCodec = null;
         String videoResolution = null;
@@ -263,6 +264,24 @@ static MediaInfo parseMediaInfo(File mediaFile, String string)
                 }
 
                 durationMs = time;
+
+                split = line.split(",");
+                for(String item : split)
+                {
+                    if(item.contains("bitrate:"))
+                    {
+                        item = item.replace("bitrate:", "").replace("kb/s", "").trim();
+                        try
+                        {
+                            // This may be used later if the video bitrate cannot be determined.
+                            totalBitrate = Integer.parseInt(item);
+                        }
+                        catch(NumberFormatException e)
+                        {
+                            continue;
+                        }
+                    }
+                }
             }
 
             if(line.startsWith("Input"))
@@ -388,6 +407,29 @@ static MediaInfo parseMediaInfo(File mediaFile, String string)
             }
         }
 
+        if(totalBitrate != null)
+        {
+            if(videoBitrate == null)
+            {
+                if(audioBitrate != null)
+                {
+                    // We know the audio bitrate, we can calculate the video bitrate
+                    videoBitrate = totalBitrate - audioBitrate;
+                }
+
+                if(videoBitrate == null)
+                {
+                    // We do not know any of the separate bitrates. Lets guess 100 kb/s for the audio,
+                    // and subtract that from the total to guess the video bitrate.
+
+                    // As a guess, subtract 100 kb/s from the bitrate for audio, and
+                    // assume that the video is the rest. This should be a decent-ish
+                    // estimate if the video bitrate cannot be found later.
+                    videoBitrate = totalBitrate - 100;
+                }
+            }
+        }
+
         MediaInfo info = new MediaInfo(mediaFile, durationMs, container, videoCodec, videoResolution,
                 videoBitrate, videoFramerate, audioCodec, audioSampleRate, audioBitrate, audioChannels);
         return info;

app/src/test/java/protect/videotranscoder/FFmpegUtilTest.java

@@ -104,12 +104,22 @@ public void parseMediaInfo() throws Exception
         assertEquals(MediaContainer.FLV, info.container);
         assertEquals(null, info.videoCodec);
         assertEquals("320x240", info.videoResolution);
-        assertEquals(null, info.videoBitrate);
+        assertEquals(Integer.valueOf(692), info.videoBitrate); // This is guessed from total bitrate
         assertEquals("25", info.videoFramerate);
         assertEquals(AudioCodec.AAC, info.audioCodec);
         assertEquals(Integer.valueOf(48000), info.audioSampleRate);
         assertEquals(null, info.audioBitrate);
         assertEquals(Integer.valueOf(2), info.audioChannels);
+
+        string = "Input #0, flv, from 'SampleVideo_360x240_1mb.flv':\n" +
+                "  Metadata:\n" + "    encoder         : Lavf53.24.2\n" +
+                "  Duration: 00:00:10.64, start: 0.000000, bitrate: 792 kb/s\n" +
+                "    Stream #0:0: Audio: aac (LC), 48000 Hz, 5.1, fltp, 92 kb/s (default)\n" +
+                "    Stream #0:1: Video: flv1, yuv420p, 320x240, 25 fps, 25 tbr, 1k tbn";
+
+        info = FFmpegUtil.parseMediaInfo(file, string);
+
+        assertEquals(Integer.valueOf(700), info.videoBitrate); // This is guessed from total and audio bitrate
     }
 
     @Test