ffmpeg cmdline generation

server/forge.py

@@ -41,13 +41,37 @@ def get_files_and_intervals(start, end, rounder=round_timefile):
         start = begin + timedelta(hours=1)
 
 
-def mp3_join(named_intervals):
+def mp3_join(named_intervals, target):
     '''
     Note that these are NOT the intervals returned by get_files_and_intervals,
     as they do not supply a filename, but only a datetime.
     What we want in input is basically the same thing, but with get_timefile()
     applied on the first element
+
+    This function make the (quite usual) assumption that the only start_cut (if
+    any) is at the first file, and the last one is at the last file
     '''
+    ffmpeg = 'ffmpeg'  # binary name
+    startskip = None
+    endskip = None
+    files = []
     for (filename, start_cut, end_cut) in named_intervals:
-        pass
-    raise NotImplementedError()
+        # this happens only one time, and only at the first iteration
+        if start_cut:
+            assert startskip is None
+            startskip = start_cut
+        # this happens only one time, and only at the first iteration
+        if end_cut:
+            assert endskip is None
+            endskip = end_cut
+        assert '|' not in filename
+        files.append(filename)
+
+    cmdline = [ffmpeg, '-i', 'concat:%s' % '|'.join(files), '-codec:a',
+               'copy']
+    if startskip is not None:
+        cmdline += ['-ss', str(startskip)]
+    if endskip is not None:
+        cmdline += ['-to', str(len(files)*3600 - endskip)]
+    cmdline += [target]
+    return cmdline

server/test_forge.py

@@ -3,7 +3,7 @@ from datetime import datetime, timedelta
 from nose.tools import raises, assert_items_equal, eq_
 
 from forge import get_files_and_intervals, get_timefile_exact, round_timefile,\
-    get_timefile
+    get_timefile, mp3_join
 
 eight = datetime(2014, 5, 30, 20)
 nine = datetime(2014, 5, 30, 21)
@@ -152,3 +152,35 @@ def test_intervals_left_2():
     eq_(res[0][2], 0)
     eq_(res[1][1], 0)
     eq_(res[1][2], 3599)
+
+# MP3 Join
+
+
+def test_mp3_1():
+    eq_(' '.join(mp3_join((('a', 0, 0),), 'foo.mp3')),
+        'ffmpeg -i concat:a -codec:a copy foo.mp3')
+
+
+def test_mp3_1_left():
+    eq_(' '.join(mp3_join((('a', 160, 0),), 'foo.mp3')),
+        'ffmpeg -i concat:a -codec:a copy -ss 160 foo.mp3')
+
+
+def test_mp3_1_right():
+    eq_(' '.join(mp3_join((('a', 0, 1600),), 'foo.mp3')),
+        'ffmpeg -i concat:a -codec:a copy -to 2000 foo.mp3')
+
+
+def test_mp3_1_leftright():
+    eq_(' '.join(mp3_join((('a', 160, 1600),), 'foo.mp3')),
+        'ffmpeg -i concat:a -codec:a copy -ss 160 -to 2000 foo.mp3')
+
+
+def test_mp3_2():
+    eq_(' '.join(mp3_join((('a', 0, 0), ('b', 0, 0)), 'foo.mp3')),
+        'ffmpeg -i concat:a|b -codec:a copy foo.mp3')
+
+
+def test_mp3_2_leftright():
+    eq_(' '.join(mp3_join((('a', 1000, 0), ('b', 0, 1600)), 'foo.mp3')),
+        'ffmpeg -i concat:a|b -codec:a copy -ss 1000 -to 5600 foo.mp3')