From 4cff7d0906fea33fa8cc6b0a4fcf4670b20c8434 Mon Sep 17 00:00:00 2001
From: Lukas Winkler <git@lw1.at>
Date: Tue, 8 Aug 2023 14:58:23 +0200
Subject: [PATCH] document a few useful cli commmands

---
 content/guide/converting-formats.md | 74 +++++++++++++++++++++++++++++
 hugo_version.txt                    |  2 +-
 layouts/_default/single.html        |  1 +
 3 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 content/guide/converting-formats.md

diff --git a/content/guide/converting-formats.md b/content/guide/converting-formats.md
new file mode 100644
index 0000000..1c5f864
--- /dev/null
+++ b/content/guide/converting-formats.md
@@ -0,0 +1,74 @@
+---
+title: "How to quickly convert file formats"
+date: 2023-08-08
+categories:
+  - collection
+  - file formats
+author: Lukas Winkler
+description: This is a collection of a few useful commands for converting files between formats that I use all the time.
+cc_license: true
+toc: true
+---
+
+This is a collection of a few useful commands for converting files between formats that I use all the time.
+
+<!--more-->
+
+## Audio
+
+### Audio → FLAC
+
+lossless if converting from e.g. WAV
+
+```bash
+flac --best input.wav
+```
+
+### Audio → Opus
+
+Check [Opus Recommended Settings](https://wiki.xiph.org/Opus_Recommended_Settings) for the ideal bitrate for your use case.
+24 Kb/s is a good basis for very small files that are still high quality for voice recordings. Only use `--downmix-mono` if you don't loose information by merging stereo audio to mono.
+
+```bash
+opusenc --bitrate 24 --downmix-mono input.wav output.opus
+```
+
+## PDFs
+
+### PDF → Extracted Images
+
+```bash
+mkdir tmp
+pdfimages input.pdf -all tmp/name
+```
+
+This will extract all images that are contained in the input pdf to `tmp/name-000.png`, `tmp/name-001.jpg`, etc.
+
+### PDF → PNG
+
+```bash
+pdftoppm input.pdf slides -png -scale-to 1080 -progress
+```
+
+This will generate images like `slides-1.png` for every page of the PDF with the specified width. With e.g. `-scale-to 3840` one can quickly convert a PDF of presentation slides to images for a high quality 4K video. 
+
+### PDF → compressed PDF
+
+[source](https://askubuntu.com/questions/113544/how-can-i-reduce-the-file-size-of-a-scanned-pdf-file/256449#256449)
+
+Sometimes I have a PDF that is far too large (hundreds of MB for a simple document) because it was generated in an ineffcient way. Using ghostscript can in many cases reduce the file size dramatically while decreasing the quality only a bit.
+
+```bash
+gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dPrinted=false -dNOPAUSE -dBATCH -sOutputFile=small.pdf input.pdf 
+```
+
+Depending on the required quality, `/ebook` can be replaced with one of `/printer`, `/prepress` and `/default` (or `/screen` for a very bad quality). See the [documentation](https://ghostscript.readthedocs.io/en/latest/VectorDevices.html#controls-and-features-specific-to-postscript-and-pdf-input) for more information
+
+### PDF → PDF with OCR
+
+```bash
+ocrmypdf -cdr --force-ocr input.pdf ocr.pdf -l deu
+```
+
+Check the [documentation](https://ocrmypdf.readthedocs.io/en/latest/cookbook.html) for more information.
+
diff --git a/hugo_version.txt b/hugo_version.txt
index 8e56006..290ac6a 100644
--- a/hugo_version.txt
+++ b/hugo_version.txt
@@ -1 +1 @@
-0.111.3
\ No newline at end of file
+0.117.0
\ No newline at end of file
diff --git a/layouts/_default/single.html b/layouts/_default/single.html
index 1e12c4e..de8cc2f 100644
--- a/layouts/_default/single.html
+++ b/layouts/_default/single.html
@@ -23,6 +23,7 @@
         </header>
         {{ partial "toc.html" . }}
         {{ .Content }}
+        <hr>
         {{ if not .Params.no_feedback }}
             <div class="alert info">You have any feedback or ideas to improve this? Contact me on Social Media or <a
                         href="mailto:guides@lw1.at">per E-Mail</a> or edit the