[README.md] Add FAQ entry for download archive

[youtube-dl] / README.md

diff --git a/README.md b/README.md
index 04f423c17cbfdaed532943ed00a1ecb1bc7310b4..1b9e2a989736a2646721fb0f73abec935b1bd205 100644 (file)
--- a/README.md
+++ b/README.md
@@ -412,11 +412,19 @@ You can configure youtube-dl by placing any supported command line option to a c
 
 For example, with the following configuration file youtube-dl will always extract the audio, not copy the mtime, use a proxy and save all videos under `Movies` directory in your home directory:
 ```
+# Lines starting with # are comments
+
+# Always extract audio
 -x
+
+# Do not copy the mtime
 --no-mtime
+
+# Use this proxy
 --proxy 127.0.0.1:3128
+
+# Save all videos under Movies directory in your home directory
 -o ~/Movies/%(title)s.%(ext)s
-# Lines starting with # are comments
 ```
 
 Note that options in configuration file are just the same options aka switches used in regular command line calls thus there **must be no whitespace** after `-` or `--`, e.g. `-o` or `--proxy` but not `- o` or `-- proxy`.
@@ -826,6 +834,18 @@ You will first need to tell youtube-dl to stream media to stdout with `-o -`, an
 
     youtube-dl -o - "http://www.youtube.com/watch?v=BaW_jenozKcj" | vlc -
 
+### How do I download only new videos from playlist?
+
+Use the download archive feature. With this feature you should initially download the complete playlist with `--download-archive /path/to/download/archive/file.txt` that will record identifiers of all the videos in a special *download archive file*. Each subsequent run with the same `--download-archive` will download only new videos that are not yet in download archive (if any) and also record them in download archive. Note that only successful downloads are recorded in download archive.
+
+For example, first run will download complete `PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re` playlist and create download archive `archive.txt`:
+
+    youtube-dl --download-archive archive.txt "https://www.youtube.com/playlist?list=PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re"
+
+Each subsequent run will only download new videos if any:
+
+    youtube-dl --download-archive archive.txt "https://www.youtube.com/playlist?list=PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re"
+
 ### Can you add support for this anime video site, or site which shows current movies for free?
 
 As a matter of policy (as well as legality), youtube-dl does not include support for services that specialize in infringing copyright. As a rule of thumb, if you cannot easily find a video that the service is quite obviously allowed to distribute (i.e. that has been uploaded by the creator, the creator's distributor, or is published under a free license), the service is probably unfit for inclusion to youtube-dl.