# RozK
# https://www.ffmpeg.org/doxygen/trunk/group__libavf.html

import ctypes

_avformat = ctypes.cdll.LoadLibrary('libavformat.so')
_avcodec = ctypes.cdll.LoadLibrary('libavcodec.so')

class AVFormatContext(ctypes.Structure):
    pass

AVFormatContext_p = ctypes.POINTER(AVFormatContext)
AVFormatContext_pp = ctypes.POINTER(AVFormatContext_p)

_avformat.avformat_alloc_context.restype = AVFormatContext_p
_avformat.avformat_alloc_context.argtypes = None

def alloc_context():
    return _avformat.avformat_alloc_context()

_avformat.avformat_free_context.restype = None
_avformat.avformat_free_context.argtypes = [AVFormatContext_p] # context

def free_context(context):
    _avformat.avformat_free_context(context)

_avformat.avformat_open_input.restype = ctypes.c_int
_avformat.avformat_open_input.argtypes = [
    AVFormatContext_pp, # context
    ctypes.c_char_p, # url
    ctypes.c_void_p, # format
    ctypes.POINTER(ctypes.c_void_p)] # options

def open_input(context, url):
    return _avformat.avformat_open_input(ctypes.byref(context), url.encode('ascii', 'ignore'), None, None)

_avformat.avformat_close_input.restype = None
_avformat.avformat_close_input.argtypes = [AVFormatContext_pp] # context

def close_input(context):
    _avformat.avformat_close_input(ctypes.byref(context))

_avformat.avformat_find_stream_info.restype = ctypes.c_int
_avformat.avformat_find_stream_info.argtypes = [
    AVFormatContext_p, # context
    ctypes.POINTER(ctypes.c_void_p)] # options

def find_stream_info(context):
    return _avformat.avformat_find_stream_info(context, None)

AVMEDIA_TYPE_UNKNOWN = -1
AVMEDIA_TYPE_VIDEO = 0
AVMEDIA_TYPE_AUDIO = 1
AVMEDIA_TYPE_DATA = 2
AVMEDIA_TYPE_SUBTITLE = 3
AVMEDIA_TYPE_ATTACHMENT = 4

class AVCodec(ctypes.Structure):
    _fields_ = [
        ("name", ctypes.c_char_p),
        ("long_name", ctypes.c_char_p)]
        # ...

AVCodec_p = ctypes.POINTER(AVCodec)
AVCodec_pp = ctypes.POINTER(AVCodec_p)

_avformat.av_find_best_stream.restype = ctypes.c_int
_avformat.av_find_best_stream.argtypes = [
    AVFormatContext_p, # context
    ctypes.c_int, # type
    ctypes.c_int, # wanted stream
    ctypes.c_int, # related stream
    AVCodec_pp, # decoder
    ctypes.c_int] # flags

def find_best_stream(context, type):
    codec = AVCodec_p()
    index = _avformat.av_find_best_stream(context, type, -1, -1, ctypes.byref(codec), 0)
    return index, codec

class AVPacket(ctypes.Structure):
    _fields_ = [
        ("buf", ctypes.c_void_p),
        ("pts", ctypes.c_int64),
        ("dts", ctypes.c_int64),
        ("data", ctypes.c_void_p),
        ("size", ctypes.c_int),
        ("stream_index", ctypes.c_int)]
        # ...

AVPacket_p = ctypes.POINTER(AVPacket)
AVPacket_pp = ctypes.POINTER(AVPacket_p)

_avformat.av_packet_alloc.restype = AVPacket_p
_avformat.av_packet_alloc.argtypes = None

def packet_alloc():
    return _avformat.av_packet_alloc()

_avformat.av_packet_free.restype = None
_avformat.av_packet_free.argtypes = [AVPacket_pp] # packet

def packet_free(packet):
    _avformat.av_packet_free(ctypes.byref(packet))

_avformat.av_read_frame.restype = ctypes.c_int
_avformat.av_read_frame.argtypes = [
    AVFormatContext_p, # context
    AVPacket_p] # packet

def read_frame(context, packet):
    return _avformat.av_read_frame(context, packet)