spaces in ffmpeg bash script filename variables - bash

Question

I am using OS X Yosemite. I want to make a simple bash script that allows me to transcode a video. Everything works well as long as a file is not located in a directory which has spaces.
Here is my script:
#!/bin/sh
ffmpeg -i “$1” -c:v ffv1 -level 3 -g 1 -c:a copy “$1.mkv”
Initially, I did not have the double quotes around the variable, but I read some stack overflows that used this as a solution. I'd rather not have to alter the path or add slashes etc. I want to just run:
./script.sh filename.mov
Here's the error I get:
Kierans-iMac:~ bla$ ./firstscript.command "/Users/bla/Desktop/untitled\ folder\ 2/v210.mov.mkv"
ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
built with Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)
configuration: --prefix=/usr/local/Cellar/ffmpeg/2.7.2_1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libfaac --enable-libass --enable-ffplay --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.2_1/include/openjpeg-1.5 ' --enable-nonfree --enable-vda
libavutil 54. 27.100 / 54. 27.100
libavcodec 56. 41.100 / 56. 41.100
libavformat 56. 36.100 / 56. 36.100
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 16.101 / 5. 16.101
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.100 / 1. 2.100
libpostproc 53. 3.100 / 53. 3.100
“/Users/bla/Desktop/untitled\: No such file or directory

Answer 1

You are quoting the spaces twice:
./firstscript.command "/Users/bla/Desktop/untitled\ folder\ 2/v210.mov.mkv"
should just be
./firstscript.command "/Users/bla/Desktop/untitled folder 2/v210.mov.mkv"
A quoted string "foo" is equivalent to \f\o\o; every character is escaped. The backslashes in your original are treated as literal backslashes.
Inside the script, you still need to quote the parameter expansion:
ffmpeg -i "$1" -c:v ffv1 -level 3 -g 1 -c:a copy "$1.mkv"
Note that you have to use regular ASCII quotes ("), not the "smart" quotes (“) implied by the error message in your link.