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

import ctypes

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

class AVFrame(ctypes.Structure):
    pass

AVFrame_p = ctypes.POINTER(AVFrame)
AVFrame_pp = ctypes.POINTER(AVFrame_p)

_avutil.av_frame_alloc.restype = AVFrame_p
_avutil.av_frame_alloc.argtypes = None

def frame_alloc():
    return _avutil.av_frame_alloc()

_avutil.av_frame_free.restype = None
_avutil.av_frame_free.argtypes = [AVFrame_pp]

def frame_free(frame):
    _avutil.av_frame_free(ctypes.byref(frame))

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 format_alloc_context():
    return _avformat.avformat_alloc_context()

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

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

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

def format_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]

def format_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,
    ctypes.POINTER(ctypes.c_void_p)] # options

def format_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,
    ctypes.c_int, # type
    ctypes.c_int, # wanted stream
    ctypes.c_int, # related stream
    AVCodec_pp,
    ctypes.c_int] # flags

def format_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]

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, AVPacket_p]

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

class AVCodecContext(ctypes.Structure):
    pass

AVCodecContext_p = ctypes.POINTER(AVCodecContext)
AVCodecContext_pp = ctypes.POINTER(AVCodecContext_p)

_avcodec.avcodec_alloc_context3.restype = AVCodecContext_p
_avcodec.avcodec_alloc_context3.argtypes = [AVCodec_p]

def codec_alloc_context(codec):
    return _avcodec.avcodec_alloc_context3(codec)

_avcodec.avcodec_free_context.restype = None
_avcodec.avcodec_free_context.argtypes = [AVCodecContext_pp]

def codec_free_context(context):
    _avcodec.avcodec_free_context(ctypes.byref(context))

_avcodec.avcodec_open2.restype = ctypes.c_int
_avcodec.avcodec_open2.argtypes = [
    AVCodecContext_p,
    AVCodec_p,
    ctypes.POINTER(ctypes.c_void_p)] # options

def codec_open(context, codec):
    return _avcodec.avcodec_open2(context, codec, None)

_avcodec.avcodec_send_packet.restype = ctypes.c_int
_avcodec.avcodec_send_packet.argtypes = [AVCodecContext_p, AVPacket_p]

def codec_send_packet(context, packet):
    return _avcodec.avcodec_send_packet(context, packet)

_avcodec.avcodec_receive_frame.restype = ctypes.c_int
_avcodec.avcodec_receive_frame.argtypes = [AVCodecContext_p, AVFrame_p]

def codec_receive_frame(context, frame):
    return _avcodec.avcodec_receive_frame(context, frame)