Answers.Body: <p><code>sine</code> is a source <em>filter</em>, so the input format needs to be set as a filter using <code>-f lavfi</code>.</p>
  
  <p>Use</p>
  
  <pre><code>ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -re -f lavfi -i sine=frequency=1000 -r 25 -vcodec libx264 -tune zerolatency -acodec aac -f mpegts udp://0.0.0.0:1234
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-01-03T15:39:37.340Z
Answers.LastActivityDate: 2019-01-03T15:39:37.340Z
Answers.UserDisplayName: Gyan
Body: <p>I'm generating an MPEG transport stream from a PNG file with <code>ffmpeg</code> succesfully with the following command:</p>
  
  <pre><code>ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -f mpegts udp://0.0.0.0:1234
  </code></pre>
  
  <p>I'd like to add an audio track to this usingthe sine function but am falling at the first hurdle.</p>
  
  <p>I've tried:</p>
  
  <pre><code>ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -i sine=frequency=1000 -f mpegts udp://0.0.0.0:1234
  </code></pre>
  
  <p>and get the error:</p>
  
  <pre><code>Unknown decoder 'libx264'
  </code></pre>
  
  <p>Which implies that my arguments order is wrong.</p>
  
  <p>So I then tried:</p>
  
  <pre><code>ffmpeg -re -loop 1 -i sine=frequency=1000 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -f mpegts udp://0.0.0.0:1234
  </code></pre>
  
  <p>and get the error:</p>
  
  <pre><code>sine=frequency=1000: No such file or directory
  </code></pre>
  
  <p>What is the correct syntax for adding a sine generated audio in this case?</p>
  
Tags: <video><ffmpeg><audio>
Title: Adding a sine generated audio track to a video stream with ffmepg
UserDisplayName: Fat Monk
ThreadText: # Adding a sine generated audio track to a video stream with ffmepg
  
  (Asked by: username_0 on 2019-01-03)
  
  I'm generating an MPEG transport stream from a PNG file with `ffmpeg` succesfully with the following command:
  
  ```
  ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -f mpegts udp://0.0.0.0:1234
  
  ```
  
  I'd like to add an audio track to this usingthe sine function but am falling at the first hurdle.
  
  I've tried:
  
  ```
  ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -i sine=frequency=1000 -f mpegts udp://0.0.0.0:1234
  
  ```
  
  and get the error:
  
  ```
  Unknown decoder 'libx264'
  
  ```
  
  Which implies that my arguments order is wrong.
  
  So I then tried:
  
  ```
  ffmpeg -re -loop 1 -i sine=frequency=1000 -i smpte-color-bars-1080p.png -r 25 -vcodec libx264 -tune zerolatency -f mpegts udp://0.0.0.0:1234
  
  ```
  
  and get the error:
  
  ```
  sine=frequency=1000: No such file or directory
  
  ```
  
  What is the correct syntax for adding a sine generated audio in this case?
  
  **Tags:** video, ffmpeg, audio
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2019-01-03. Score: 0 | Accepted answer
  
  `sine` is a source *filter*, so the input format needs to be set as a filter using `-f lavfi`.
  
  Use
  
  ```
  ffmpeg -re -loop 1 -i smpte-color-bars-1080p.png -re -f lavfi -i sine=frequency=1000 -r 25 -vcodec libx264 -tune zerolatency -acodec aac -f mpegts udp://0.0.0.0:1234
  
  ```
  
  
  ---
  
  