Allow to read resized frames

moviepy/video/io/VideoFileClip.py

@@ -32,6 +32,17 @@ class VideoFileClip(VideoClip):
     audio:
       Set to `False` if the clip doesn't have any audio or if you do not
       wish to read the audio.
+
+    target_resolution:
+      Set to (desired_height, desired_width) to have ffmpeg resize the frames before return them.
+      This is much faster than streaming in high-res and then resizing.
+      if either size is None, the frames are resized by keeping the existing aspect ratio.
+
+    resize_algorithm:
+      The algorithm used for resizing. Default: "bicubic", other popular options include "bilinear"
+      and "fast_bilinear".
+      For more information, see https://ffmpeg.org/ffmpeg-scaler.html
+
       
     Attributes
     -----------
@@ -48,14 +59,16 @@ class VideoFileClip(VideoClip):
 
     def __init__(self, filename, has_mask=False,
                  audio=True, audio_buffersize = 200000,
+                 target_resolution=None, resize_algorithm='bicubic',
                  audio_fps=44100, audio_nbytes=2, verbose=False):
 
         VideoClip.__init__(self)
-        
+
         # Make a reader
         pix_fmt= "rgba" if has_mask else "rgb24"
         self.reader = None #need this just in case FFMPEG has issues (__del__ complains)
-        self.reader = FFMPEG_VideoReader(filename, pix_fmt=pix_fmt)
+        self.reader = FFMPEG_VideoReader(filename, pix_fmt=pix_fmt,
+                                    target_resolution=target_resolution, resize_algo=resize_algorithm)
         # Make some of the reader's attributes accessible from the clip
         self.duration = self.reader.duration
         self.end = self.reader.duration

moviepy/video/io/ffmpeg_reader.py

@@ -23,12 +23,24 @@
 class FFMPEG_VideoReader:
 
     def __init__(self, filename, print_infos=False, bufsize = None,
-                 pix_fmt="rgb24", check_duration=True):
+                 pix_fmt="rgb24", check_duration=True,
+                 target_resolution=None, resize_algo='bicubic'):
 
         self.filename = filename
         infos = ffmpeg_parse_infos(filename, print_infos, check_duration)
         self.fps = infos['video_fps']
         self.size = infos['video_size']
+        if target_resolution:
+            if None in target_resolution:
+                ratio=1
+                for idx, target in enumerate(target_resolution):
+                    if target:
+                        ratio = min(ratio,float(target)/self.size[idx])
+                self.size = (int(self.size[0]*ratio),int(self.size[1]*ratio))
+            else:
+                self.size = target_resolution
+        self.resize_algo = resize_algo
+
         self.duration = infos['video_duration']
         self.ffmpeg_duration = infos['duration']
         self.nframes = infos['video_nframes']
@@ -66,13 +78,13 @@ def initialize(self, starttime=0):
         else:
             i_arg = [ '-i', self.filename]
 
-
         cmd = ([get_setting("FFMPEG_BINARY")]+ i_arg +
                 ['-loglevel', 'error',
                 '-f', 'image2pipe',
+                '-vf', 'scale=%d:%d' % tuple(self.size),
+                '-sws_flags', self.resize_algo,
                 "-pix_fmt", self.pix_fmt,
                 '-vcodec', 'rawvideo', '-'])
-
         popen_params = {"bufsize": self.bufsize,
                         "stdout": sp.PIPE,
                         "stderr": sp.PIPE,