Prepare code for audio recording

Now, state->frame_lengths contains not only video frames lengths but audio
sample lengths as well if audio recording is enabled.

src/camogm.h

@@ -222,10 +222,17 @@ typedef struct {
 	double start_after_timestamp;                           ///< delay recording start to after frame timestamp
 	int max_frames;
 	int set_max_frames;
-	int frames_per_chunk;
-	int set_frames_per_chunk;                               ///< quicktime -  index for fast forward?
-	int frameno;
-	int *frame_lengths;
+	int frames_per_chunk;                                   ///< QuickTime, the number of samples (images or audio samples) in a chunk
+	int set_frames_per_chunk;                               ///< QuickTime, index for fast forward (sample-to-chunk atom)
+	int frameno;                                            ///< total image frame counter, does not include audio samples
+	unsigned long *frame_lengths;                           ///< QuickTime; pointer to an array of frame lengths wich includes both image frames
+	                                                        ///< and audio samples if audio recording is enabled. MSB of each entry indicates
+	                                                        ///< the type of frame this length relates to: if MSB = 0 then this is images frame and
+	                                                        ///< if MSB = 1 then this is audio sample. Stealing one bit from the length field
+	                                                        ///< effectively limits the size of one frame to 2 GiB which should be more than enough
+	                                                        ///< for all purposes.
+	long frame_index;                                       ///< QuickTime; total frame counter including audio samples (if enabled), this is used
+	                                                        ///< as an index for frame_lengths array
 	off_t frame_data_start;                                 ///< Quicktime (and else?) - frame data start (0xff 0xd8...)
 	ogg_int64_t time_unit;
 	int formats;                                            ///< bitmask of used (initialized) formats

src/camogm_audio.c

@@ -50,7 +50,7 @@ void audio_init(struct audio *audio, bool restart)
 	}
 	// set up audio device
 	if (restart) {
-		int err;
+		int err = 0;
 		bool init_ok = false;
 		unsigned int t = audio->audio_rate;
 		unsigned int period_time = 40 * 1000;

src/qt_audio

@@ -293,7 +293,7 @@
 #     0017
 #	 0020
 #   }
-#   00000000	# ???
+#   00000000	# optional terminating 32-bit value, see description of User Data Atom
 # }
 }
   !data_size

src/qt_source

@@ -151,7 +151,7 @@
      0017
 	 0020
    }
-   00000000	# ???
+   00000000	# optional terminating 32-bit value, see description of User Data Atom
  }
 }
   !data_size