Another try for fixing/improving decode_video documentation.

Originally committed as revision 23057 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -3474,8 +3474,8 @@ attribute_deprecated int avcodec_decode_video(AVCodecContext *avctx, AVFrame *pi
  *
  * @param avctx the codec context
  * @param[out] picture The AVFrame in which the decoded video frame will be stored.
- *             Use avcodec_alloc_frame to get an AVFrame, the codec will call
- *             get_buffer to get memory for the actual image data.
+ *             Use avcodec_alloc_frame to get an AVFrame, the codec will
+ *             allocate memory for the actual bitmap.
  * @param[in] avpkt The input AVpacket containing the input buffer.
  *            You can create such packet with av_init_packet() and by then setting
  *            data and size, some decoders might in addition need other fields like