decoder

mp4/libav.py

@@ -1,12 +1,36 @@
 # RozK
 # https://www.ffmpeg.org/doxygen/trunk/group__libavf.html
 
+import errno
 import ctypes
 
 _avutil = ctypes.cdll.LoadLibrary('libavutil.so')
 _avformat = ctypes.cdll.LoadLibrary('libavformat.so')
 _avcodec = ctypes.cdll.LoadLibrary('libavcodec.so')
 
+def _errtag(a, b, c, d):
+    return -(ord(a) | (ord(b) << 8) | (ord(c) << 16) | (ord(d) << 24))
+
+if errno.EAGAIN < 0:
+    AVERROR_EAGAIN = errno.EAGAIN
+else:
+    AVERROR_EAGAIN = -errno.EAGAIN
+
+AVERROR_EOF = _errtag('E', 'O', 'F', ' ')
+
+AV_ERROR_MAX_STRING_SIZE = 64
+
+_avutil.av_strerror.restype = ctypes.c_int
+_avutil.av_strerror.argtypes = [
+    ctypes.c_int, # errno
+    ctypes.c_char_p, # errbuf
+    ctypes.c_size_t] # errbuff_size
+
+def strerror(errno):
+    errbuf = ctypes.create_string_buffer(AV_ERROR_MAX_STRING_SIZE)
+    _avutil.av_strerror(errno, errbuf, AV_ERROR_MAX_STRING_SIZE)
+    return errbuf.value.decode("utf-8")
+
 class AVFrame(ctypes.Structure):
     pass
 
@@ -25,9 +49,34 @@ _avutil.av_frame_free.argtypes = [AVFrame_pp]
 def frame_free(frame):
     _avutil.av_frame_free(ctypes.byref(frame))
 
-class AVFormatContext(ctypes.Structure):
+class AVCodecParameters(ctypes.Structure):
     pass
 
+AVCodecParameters_p = ctypes.POINTER(AVCodecParameters)
+
+class AVStream(ctypes.Structure):
+    _fields_ = [
+        ("av_class", ctypes.c_void_p),
+        ("index", ctypes.c_int),
+        ("id", ctypes.c_int),
+        ("codecpar", AVCodecParameters_p)]
+        # ...
+
+AVStream_p = ctypes.POINTER(AVStream)
+AVStream_pp = ctypes.POINTER(AVStream_p)
+
+class AVFormatContext(ctypes.Structure):
+    _fields_ = [
+        ("av_class", ctypes.c_void_p),
+        ("iformat", ctypes.c_void_p),
+        ("oformat", ctypes.c_void_p),
+        ("priv_data", ctypes.c_void_p),
+        ("pb", ctypes.c_void_p),
+        ("ctx_flags", ctypes.c_int),
+        ("nb_streams", ctypes.c_uint),
+        ("streams", AVStream_pp)]
+        # ...
+
 AVFormatContext_p = ctypes.POINTER(AVFormatContext)
 AVFormatContext_pp = ctypes.POINTER(AVFormatContext_p)
 
@@ -146,6 +195,12 @@ _avcodec.avcodec_free_context.argtypes = [AVCodecContext_pp]
 def codec_free_context(context):
     _avcodec.avcodec_free_context(ctypes.byref(context))
 
+_avcodec.avcodec_parameters_to_context.restype = ctypes.c_int
+_avcodec.avcodec_parameters_to_context.argtypes = [AVCodecContext_p, AVCodecParameters_p]
+
+def codec_parameters_to_context(context, parameters):
+    return _avcodec.avcodec_parameters_to_context(context, parameters)
+
 _avcodec.avcodec_open2.restype = ctypes.c_int
 _avcodec.avcodec_open2.argtypes = [
     AVCodecContext_p,