Let user specified input audio codec and not relay on the default one

av/container/core.pyx

@@ -168,13 +168,52 @@ Flags = define_enum('Flags', __name__, (
 ), is_flags=True)
 
 
+AudioCodecs = define_enum('AudioCodecs', __name__, (
+    ('NONE', lib.AV_CODEC_ID_NONE),
+    ('PCM_ALAW', lib.AV_CODEC_ID_PCM_ALAW),
+    ('PCM_BLURAY', lib.AV_CODEC_ID_PCM_BLURAY),
+    ('PCM_DVD', lib.AV_CODEC_ID_PCM_DVD),
+    ('PCM_F16LE', lib.AV_CODEC_ID_PCM_F16LE),
+    ('PCM_F24LE', lib.AV_CODEC_ID_PCM_F24LE),
+    ('PCM_F32BE', lib.AV_CODEC_ID_PCM_F32BE),
+    ('PCM_F32LE', lib.AV_CODEC_ID_PCM_F32LE),
+    ('PCM_F64BE', lib.AV_CODEC_ID_PCM_F64BE),
+    ('PCM_F64LE', lib.AV_CODEC_ID_PCM_F64LE),
+    ('PCM_LXF', lib.AV_CODEC_ID_PCM_LXF),
+    ('PCM_MULAW', lib.AV_CODEC_ID_PCM_MULAW),
+    ('PCM_S16BE', lib.AV_CODEC_ID_PCM_S16BE),
+    ('PCM_S16BE_PLANAR', lib.AV_CODEC_ID_PCM_S16BE_PLANAR),
+    ('PCM_S16LE', lib.AV_CODEC_ID_PCM_S16LE),
+    ('PCM_S16LE_PLANAR', lib.AV_CODEC_ID_PCM_S16LE_PLANAR),
+    ('PCM_S24BE', lib.AV_CODEC_ID_PCM_S24BE),
+    ('PCM_S24DAUD', lib.AV_CODEC_ID_PCM_S24DAUD),
+    ('PCM_S24LE', lib.AV_CODEC_ID_PCM_S24LE),
+    ('PCM_S24LE_PLANAR', lib.AV_CODEC_ID_PCM_S24LE_PLANAR),
+    ('PCM_S32BE', lib.AV_CODEC_ID_PCM_S32BE),
+    ('PCM_S32LE', lib.AV_CODEC_ID_PCM_S32LE),
+    ('PCM_S32LE_PLANAR', lib.AV_CODEC_ID_PCM_S32LE_PLANAR),
+    ('PCM_S64BE', lib.AV_CODEC_ID_PCM_S64BE),
+    ('PCM_S64LE', lib.AV_CODEC_ID_PCM_S64LE),
+    ('PCM_S8', lib.AV_CODEC_ID_PCM_S8),
+    ('PCM_S8_PLANAR', lib.AV_CODEC_ID_PCM_S8_PLANAR),
+    ('PCM_U16BE', lib.AV_CODEC_ID_PCM_U16BE),
+    ('PCM_U16LE', lib.AV_CODEC_ID_PCM_U16LE),
+    ('PCM_U24BE', lib.AV_CODEC_ID_PCM_U24BE),
+    ('PCM_U24LE', lib.AV_CODEC_ID_PCM_U24LE),
+    ('PCM_U32BE', lib.AV_CODEC_ID_PCM_U32BE),
+    ('PCM_U32LE', lib.AV_CODEC_ID_PCM_U32LE),
+    ('PCM_U8', lib.AV_CODEC_ID_PCM_U8),
+    ('PCM_VIDC', lib.AV_CODEC_ID_PCM_VIDC)
+))
+
+
 cdef class Container(object):
 
     def __cinit__(self, sentinel, file_, format_name, options,
                   container_options, stream_options,
                   metadata_encoding, metadata_errors,
                   buffer_size, open_timeout, read_timeout,
-                  io_open):
+                  io_open, audio_codec=None):
 
         if sentinel is not _cinit_sentinel:
             raise RuntimeError('cannot construct base Container')
@@ -240,6 +279,9 @@ cdef class Container(object):
         self.ptr.flags |= lib.AVFMT_FLAG_GENPTS
         self.ptr.opaque = <void*>self
 
+        if audio_codec is not None:
+            self.ptr.audio_codec_id = AudioCodecs[audio_codec]
+
         # Setup Python IO.
         self.open_files = {}
         if not isinstance(file_, basestring):
@@ -338,7 +380,8 @@ cdef class Container(object):
 def open(file, mode=None, format=None, options=None,
          container_options=None, stream_options=None,
          metadata_encoding='utf-8', metadata_errors='strict',
-         buffer_size=32768, timeout=None, io_open=None):
+         buffer_size=32768, timeout=None, io_open=None,
+         audio_codec=None):
     """open(file, mode='r', **kwargs)
 
     Main entrypoint to opening files/streams.
@@ -365,6 +408,10 @@ def open(file, mode=None, format=None, options=None,
         ``url`` is the url to open, ``flags`` is a combination of AVIO_FLAG_* and
         ``options`` is a dictionary of additional options. The callable should return a
         file-like object.
+    :param str audio_codec: Specify audio input codec to be used when reading
+        form ALSA or PulseAudio devices. For example ``"PCM_S32LE"`` or
+        ``"PCM_S16BE"``. If not given, the codec is left unconfigured and
+        defaults to FFmpeg default.
 
     For devices (via ``libavdevice``), pass the name of the device to ``format``,
     e.g.::
@@ -397,13 +444,19 @@ def open(file, mode=None, format=None, options=None,
         open_timeout = timeout
         read_timeout = timeout
 
+    if audio_codec is not None:
+        try:
+            AudioCodecs[audio_codec]
+        except KeyError:
+            raise ValueError("Provided audio_codec must be one of the supported audio codecs")
+
     if mode.startswith('r'):
         return InputContainer(
             _cinit_sentinel, file, format, options,
             container_options, stream_options,
             metadata_encoding, metadata_errors,
             buffer_size, open_timeout, read_timeout,
-            io_open
+            io_open, audio_codec
         )
     if mode.startswith('w'):
         if stream_options:

include/libavcodec/avcodec.pxd

@@ -115,6 +115,41 @@ cdef extern from "libavcodec/avcodec.h" nogil:
         AV_CODEC_ID_NONE
         AV_CODEC_ID_MPEG2VIDEO
         AV_CODEC_ID_MPEG1VIDEO
+        # Audio codecs.
+        AV_CODEC_ID_PCM_ALAW
+        AV_CODEC_ID_PCM_BLURAY
+        AV_CODEC_ID_PCM_DVD
+        AV_CODEC_ID_PCM_F16LE
+        AV_CODEC_ID_PCM_F24LE
+        AV_CODEC_ID_PCM_F32BE
+        AV_CODEC_ID_PCM_F32LE
+        AV_CODEC_ID_PCM_F64BE
+        AV_CODEC_ID_PCM_F64LE
+        AV_CODEC_ID_PCM_LXF
+        AV_CODEC_ID_PCM_MULAW
+        AV_CODEC_ID_PCM_S16BE
+        AV_CODEC_ID_PCM_S16BE_PLANAR
+        AV_CODEC_ID_PCM_S16LE
+        AV_CODEC_ID_PCM_S16LE_PLANAR
+        AV_CODEC_ID_PCM_S24BE
+        AV_CODEC_ID_PCM_S24DAUD
+        AV_CODEC_ID_PCM_S24LE
+        AV_CODEC_ID_PCM_S24LE_PLANAR
+        AV_CODEC_ID_PCM_S32BE
+        AV_CODEC_ID_PCM_S32LE
+        AV_CODEC_ID_PCM_S32LE_PLANAR
+        AV_CODEC_ID_PCM_S64BE
+        AV_CODEC_ID_PCM_S64LE
+        AV_CODEC_ID_PCM_S8
+        AV_CODEC_ID_PCM_S8_PLANAR
+        AV_CODEC_ID_PCM_U16BE
+        AV_CODEC_ID_PCM_U16LE
+        AV_CODEC_ID_PCM_U24BE
+        AV_CODEC_ID_PCM_U24LE
+        AV_CODEC_ID_PCM_U32BE
+        AV_CODEC_ID_PCM_U32LE
+        AV_CODEC_ID_PCM_U8
+        AV_CODEC_ID_PCM_VIDC
 
     cdef enum AVDiscard:
         AVDISCARD_NONE

include/libavformat/avformat.pxd

@@ -177,6 +177,9 @@ cdef extern from "libavformat/avformat.h" nogil:
 
         AVDictionary *metadata
 
+        # Forced audio codec set by user.
+        AVCodecID audio_codec_id
+
         char filename
         int64_t start_time
         int64_t duration

tests/test_errors.py

@@ -67,3 +67,11 @@ def test_buffertoosmall(self):
             self.assertEqual(e.errno, av.error.BUFFER_TOO_SMALL.value)
         else:
             self.fail("no exception raised")
+
+    def test_not_supported_audio_codec(self):
+        try:
+            av.open("alsa_device", audio_codec="does_not_exist")
+        except ValueError as e:
+            self.assertEqual(str(e), "Provided audio_codec must be one of the supported audio codecs")
+        else:
+            self.fail("no exception raised")