(Very) Thin FFMpeg C binding for Nim. The thin binding means it's almost same
with FFMpeg C APIs.
The advantage is that we can reuse our C APIs knowledge using Nim seamlessly. We
can reuse any FFMpeg C tutorials to work with.
Some snippet here can be used to get the first 5 video frame
var frameCount = 0
while frameCount < 5:
if av_read_frame(pFrameContext, pPacket) < 0: # negative means it's error
continue # and we just skip this time
if packet[].stream_index == videoIndex: # we only process packet in specific index stream
# in this case it's video stream
if avcodec_send_packet(pVideoCodecCtx, pPacket) < 0: # negative means it's error
continue
if avcodec_receive_frame(pVideoCodecCtx, pFrame) < 0:
continue
doSomethingWith3YUVPlaneData(pFrame[].data) # pFrame[].data is array filled with YUV several planes
# pFrame[].data[0] is Y plane
# pFrame[].data[1] is U plane (or Cb be precise)
# pFrame[].data[2] is V plane (or Cr be precise)
inc frameCount
Snippet to get the first video stream index
var videoIndex = -1
var streams = cast[ptr UncheckedArray[ptr AVStream]](pFormatCtx[].streams)
for i in 0 .. pFormatCtx[].nb_streams:
let localparam = streams[i][].codecpar
if localparam[].codec_type == AVMEDIA_TYPE_VIDEO:
videoIndex = int i
break
The index can be used later to know which stream index packet we'll process later.
Any others examples you found should be applicable with this binding too. Several worked examples
also availables in examples folder.
To able to compile and work with, make sure we installed shared lib to run it.