Kilian's homepage and public feed Zola 2025-08-20T00:00:00+00:00 https://kilko.de/tags/ffmpeg/atom.xml 2025-08-20T00:00:00+00:00 2025-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/change-video-container/ <p>Quickly change a file's container using <em>magic</em> shell syntax.</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">ffmpeg</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> path/to/file.{webm,</span><span class="z-string"> mp4}</span></span></code></pre> 2025-08-20T00:00:00+00:00 2025-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/concatenate-videos/ <p>Concating several video files with ffmpeg is very straightforward if they all share the same container and codec. Add all input files to a text file listing their relative or absolute paths.</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">file</span><span class="z-punctuation z-definition z-string"> &#39;</span><span class="z-string">file1.mp4</span><span class="z-punctuation z-definition z-string">&#39;</span></span> <span class="giallo-l"><span class="z-entity z-name">file</span><span class="z-punctuation z-definition z-string"> &#39;</span><span class="z-string">file2.mp4</span><span class="z-punctuation z-definition z-string">&#39;</span></span> <span class="giallo-l"><span class="z-support">.</span><span class="z-support">.</span><span class="z-support">.</span></span></code></pre> <p>Run the following.</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">$</span><span class="z-string"> ffmpeg</span><span class="z-constant"> -</span><span class="z-constant">f</span><span class="z-string"> concat</span><span class="z-constant"> -</span><span class="z-constant">safe</span><span class="z-constant"> 0</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> input.txt</span><span class="z-constant"> -</span><span class="z-constant">c</span><span class="z-string"> copy</span><span class="z-string"> output.mp4</span></span></code></pre> <p><code>-safe 0</code> can be omitted if the filepaths are relative.</p> 2025-08-20T00:00:00+00:00 2025-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/create-video-from-image-and-audio/ <p>Technically something simple along the following lines would work.</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">ffmpeg</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> image.png</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> audio.mp3</span><span class="z-string"> video.mp4</span></span></code></pre> <p>This does however create a file with just a single frame, which doesn't really work on YouTube for example. The following creates a video with repeating frames.</p> <pre class="giallo z-code"><code data-lang="javascript"><span class="giallo-l"><span class="z-variable z-other">ffmpeg</span><span class="z-keyword"> -</span><span class="z-variable z-other">r</span><span class="z-constant"> 1</span><span class="z-keyword"> -</span><span class="z-variable z-other">loop</span><span class="z-constant"> 1</span><span class="z-keyword"> -</span><span class="z-variable z-other">i</span><span class="z-variable z-other"> image</span><span>.</span><span class="z-variable z-other">png</span><span class="z-keyword"> -</span><span class="z-variable z-other">i</span><span class="z-variable z-other"> audio</span><span>.</span><span class="z-variable z-other">mp3</span><span class="z-keyword"> -</span><span class="z-variable z-other">acodec</span><span class="z-variable z-other"> copy</span><span class="z-keyword"> -</span><span class="z-variable z-other">shortest</span><span class="z-keyword"> -</span><span class="z-variable z-other">vf</span><span class="z-variable z-other"> scale</span><span class="z-keyword">=</span><span class="z-constant">1280</span><span>:</span><span class="z-constant">720</span><span class="z-variable z-other"> video</span><span>.</span><span class="z-variable z-other">mp4</span></span></code></pre> <p>Credits go to <a rel="external" href="https://superuser.com/a/1041820/236423">superuser.com/a/1041820/236423</a></p> 2025-08-20T00:00:00+00:00 2025-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/keep-subtiles-while-transcoding/ <p>To keep all existent subtitle tracks when transcoding media with ffmpeg, just pass the flag <code>-map 0:s -c copy</code>, e.g.</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">$</span><span class="z-string"> ffmpeg</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> /path/to/media.{mkv,mp4}</span><span class="z-constant"> -</span><span class="z-constant">map</span><span class="z-string"> 0:s</span><span class="z-constant"> -</span><span class="z-constant">c</span><span class="z-string"> copy</span></span></code></pre> 2025-08-20T00:00:00+00:00 2025-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/rotate-videos/ <p>Rotate videos using ffmpeg by transposing them. The command to do so is:</p> <pre class="giallo z-code"><code data-lang="shellscript"><span class="giallo-l"><span class="z-entity z-name">$</span><span class="z-string"> ffmpeg</span><span class="z-constant"> -</span><span class="z-constant">i</span><span class="z-string"> input.mp4</span><span class="z-constant"> -</span><span class="z-constant">vf</span><span class="z-punctuation z-definition z-string"> &quot;</span><span class="z-string">transpose=1</span><span class="z-punctuation z-definition z-string">&quot;</span><span class="z-string"> output.mp4</span></span></code></pre> <p>The possible rotations are the following.</p> <pre class="giallo z-code"><code data-lang="plain"><span class="giallo-l"><span>0 = 90CounterCLockwise and Vertical Flip (default)</span></span> <span class="giallo-l"><span>1 = 90Clockwise</span></span> <span class="giallo-l"><span>2 = 90CounterClockwise</span></span> <span class="giallo-l"><span>3 = 90Clockwise and Vertical Flip</span></span></code></pre> <p>Use <code>-vf "transpose=2,transpose=2"</code> for 180 degrees.</p> <p>Credits go to <a rel="external" href="https://stackoverflow.com/a/9570992/1843020">stackoverflow.com/a/9570992/1843020</a></p>