def __init__(self, formatCtx, size, frameRate, pixelAspect):
"""Constructor.
formatCtx is a AVFormatContext object.
size is a tuple (width, height) containing the resolution of the
video images.
frameRate is the target framerate. It can be a single int or float
or a tuple (num,den).
pixelAspect is a float containing the pixel aspect ratio.
"""
self._formatCtx = formatCtx
self._size = size
self._pixelAspect = pixelAspect
try:
# Check if frameRate is a 2-tuple
num,den = frameRate
except:
# Turn the framerate into a rational...
r = avutil.av_d2q(frameRate, 255)
frameRate = (r.num, r.den)
# The framerate as a tuple (num, den).
self._frameRate = frameRate
# Create an AVStream
self._stream = self._createStream()
# Get the codec context of the stream
self._codecCtx = self._stream.codec.contents
width,height = self._size
# Set up the buffer that can store the encoded frame
self._bufSize = 6*width*height+200
self._buffer = ctypes.create_string_buffer(self._bufSize)
self._frame = avcodec.avcodec_alloc_frame()
if self._frame is None:
raise MemoryError("Failed to allocate AVFrame object")
avcodec.avpicture_alloc(self._frame, self._codecCtx.pix_fmt, width, height)
# Allocate a picture for the converted image...
self._picture = decls.AVPicture()
avcodec.avpicture_alloc(self._picture, self._codecCtx.pix_fmt, width, height)
# Get the size of the destination image buffer
self._pictureSize = avcodec.avpicture_get_size(self._codecCtx.pix_fmt, width, height)
self._pkt = decls.AVPacket()
avformat.av_init_packet(self._pkt)
#pkt.stream_index = outputstream.index
self._currentPts = 0
def _initPilProcessing(self):
"""Initialize decoding into a PIL image.
Initializes an intermediate buffer (AVPicture) that will receive
the converted image and a swscale context to do the conversion.
"""
width,height = self.size
dstPixFmt = decls.PIX_FMT_RGB24
# In case, this is called several times, make sure we don't leak memory.
self._free()
# Allocate a buffer that can hold the converted image
self._picture = decls.AVPicture()
avcodec.avpicture_alloc(self._picture, dstPixFmt, width, height)
# Get the size of the destination image buffer
self._pictureSize = avcodec.avpicture_get_size(dstPixFmt, width, height)
# Allocate the swscale context
self._pilSwsCtx = swscale.sws_getContext(width, height, self._srcPixFmt,
width, height, dstPixFmt, 1)
