add bbb download info fixes #34

Author: leandromoreira

Makefile

@@ -1,6 +1,9 @@
 clean:
 	@rm -rf ./build/*
 
+fetch_small_bunny_video:
+	./fetch_bbb_video.sh
+
 make_hello: clean
 	docker run -w /files --rm -it  -v `pwd`:/files leandromoreira/ffmpeg-devel \
 	  gcc -L/opt/ffmpeg/lib -I/opt/ffmpeg/include/ /files/0_hello_world.c \

README.md

@@ -289,7 +289,7 @@ The `AVCodec` will decode them into [`AVFrame`](https://ffmpeg.org/doxygen/trunk
 
 ### Requirements
 
-Since some people were [facing issues while compiling or running the examples](https://github.com/leandromoreira/ffmpeg-libav-tutorial/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+compiling) **we're going to use [`Docker`](https://docs.docker.com/install/) as our development/runner environment.**
+Since some people were [facing issues while compiling or running the examples](https://github.com/leandromoreira/ffmpeg-libav-tutorial/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+compiling) **we're going to use [`Docker`](https://docs.docker.com/install/) as our development/runner environment,** we'll also use the big buck bunny video so if you don't have it locally just run the command `make fetch_small_bunny_video`.
 
 ### Chapter 0 - code walkthrough
 

fetch_bbb_video.sh

@@ -0,0 +1,20 @@
+read -p "WARNING: You're about to download 340MB, are you sure? (yN) " -n 1 -r
+echo    # (optional) move to a new line
+if [[ ! $REPLY =~ ^[Yy]$ ]]
+then
+  echo "n"
+  [[ "$0" = "$BASH_SOURCE" ]] && exit 1 || return 1 # handle exits from shell or function but don't exit interactive shell
+fi
+
+check_cmd()
+{
+  if ! which $1 &>/dev/null; then
+    error "$1 command not found, you must install it before."
+  fi
+}
+
+check_cmd wget
+check_cmd ffmpeg
+
+wget -O bunny_1080p_60fps.mp4 http://distribution.bbb3d.renderfarming.net/video/mp4/bbb_sunflower_1080p_60fps_normal.mp4
+ffmpeg -y -i bunny_1080p_60fps.mp4 -ss 00:01:24 -t 00:00:10 small_bunny_1080p_60fps.mp4