Fix an issue related to synchronization of recordings when using Monitor().

The bug is a miscalculation of the amount to seek the stream for writing to
disk when the number of samples coming in and out of a channel do not match up.
(issue #8298, #8887, report and patch by guillecabeza, patch files created and
 testing done by whoiswes)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@51843 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channel.c

@@ -1958,9 +1958,10 @@ struct ast_frame *ast_read(struct ast_channel *chan)
 #ifndef MONITOR_CONSTANT_DELAY
 				int jump = chan->outsmpl - chan->insmpl - 4 * f->samples;
 				if (jump >= 0) {
-					if (ast_seekstream(chan->monitor->read_stream, jump + f->samples, SEEK_FORCECUR) == -1)
+					jump = chan->outsmpl - chan->insmpl;
+					if (ast_seekstream(chan->monitor->read_stream, jump, SEEK_FORCECUR) == -1)
 						ast_log(LOG_WARNING, "Failed to perform seek in monitoring read stream, synchronization between the files may be broken\n");
-					chan->insmpl += jump + 4 * f->samples;
+					chan->insmpl += jump + f->samples;
 				} else
 					chan->insmpl+= f->samples;
 #else
@@ -2313,9 +2314,10 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
 #ifndef MONITOR_CONSTANT_DELAY
 					int jump = chan->insmpl - chan->outsmpl - 4 * f->samples;
 					if (jump >= 0) {
-						if (ast_seekstream(chan->monitor->write_stream, jump + f->samples, SEEK_FORCECUR) == -1)
+						jump = chan->insmpl - chan->outsmpl;
+						if (ast_seekstream(chan->monitor->write_stream, jump, SEEK_FORCECUR) == -1)
 							ast_log(LOG_WARNING, "Failed to perform seek in monitoring write stream, synchronization between the files may be broken\n");
-						chan->outsmpl += jump + 4 * f->samples;
+						chan->outsmpl += jump + f->samples;
 					} else
 						chan->outsmpl += f->samples;
 #else