Answers.Body: <p>ffmpeg is a good choice for this task. You can do this with this command:</p>
  
  <pre><code>ffmpeg -i input.mp4 -i input_audio.aac -map 0:0 -map 1 -vcodec copy -acodec copy output.mp4
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-10-11T07:23:15.093Z
Answers.LastActivityDate: 2014-10-11T13:45:30.467Z
Answers.LastEditDate: 2014-10-11T13:45:30.467Z
Answers.UserDisplayName: amimciptimdim
Answers.Body: <p>Yes, ffmpeg can do what you need, which is to demux the MP4 into audio and video components, then remux using the new audio. Actually, you can extract just the video since you don't need the existing audio. I'm not an expert in ffmpeg, but the demux command line would be something like <strong><em>ffmpeg -i myfile.mp4 -vcodec copy myvideo.h264</em></strong>. </p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-10-11T13:58:04.317Z
Answers.Text: See amimciptimdim command for remuxing the .h264 into a new mp4. Instead of input.mp4 you provide the path to your myvideo.h264.
Answers.UserDisplayName: timonsku
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-10-11T16:59:04.047Z
Answers.Text: Yes, actually it looks as if you can do it in one step: combine the video from the original MP4 and a new AAC/MP3 into a new MP4.
Answers.UserDisplayName: Jim Mack
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-10-11T18:01:31.200Z
Answers.Text: You could endup with 2 audio stream though depending on how the original audio is mapped in the container and how ffmpeg handles this situation, it either creates a second audio stream or replaces the first when using -map 1.
Answers.UserDisplayName: timonsku
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-10-10T10:25:48.573Z
Answers.LastActivityDate: 2014-10-10T10:25:48.573Z
Answers.UserDisplayName: Jim Mack
Body: <p>Is there any way to swap out the audio track on a rendered H.264 MPEG-4 without having to re-render the entire video project? Can this be done with Premiere, MPEG Streamclip, ffmpeg, or some other tool that I'm not familiar with ?</p>
  
  <p>I have a long video project that took many hours to render, and I would like to swap out the audio (minor mixing changes) without having to re-render the entire video project. The new audio is exactly the same length.</p>
  
  <p>Is this feasible? I'm primarily a Premiere user, but I'm happy to hear solutions for other tools.</p>
  
Tags: <premiere><audio><mp4>
Title: How do I change the audio on a H.264 MP4 without re-rendering the file?
UserDisplayName: bryan kennedy
ThreadText: # How do I change the audio on a H.264 MP4 without re-rendering the file?
  
  (Asked by: username_0 on 2014-10-09)
  
  Is there any way to swap out the audio track on a rendered H.264 MPEG-4 without having to re-render the entire video project? Can this be done with Premiere, MPEG Streamclip, ffmpeg, or some other tool that I'm not familiar with ?
  
  I have a long video project that took many hours to render, and I would like to swap out the audio (minor mixing changes) without having to re-render the entire video project. The new audio is exactly the same length.
  
  Is this feasible? I'm primarily a Premiere user, but I'm happy to hear solutions for other tools.
  
  **Tags:** premiere, audio, mp4
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2014-10-11. Score: 3
  
  ffmpeg is a good choice for this task. You can do this with this command:
  
  ```
  ffmpeg -i input.mp4 -i input_audio.aac -map 0:0 -map 1 -vcodec copy -acodec copy output.mp4
  
  ```
  
  
  ---
  
  ### Answer by username_2 on 2014-10-10. Score: 2
  
  Yes, ffmpeg can do what you need, which is to demux the MP4 into audio and video components, then remux using the new audio. Actually, you can extract just the video since you don't need the existing audio. I'm not an expert in ffmpeg, but the demux command line would be something like ***ffmpeg -i myfile.mp4 -vcodec copy myvideo.h264***.
  
  > **Comments:**
  > **username_3**: See username_1 command for remuxing the .h264 into a new mp4. Instead of input.mp4 you provide the path to your myvideo.h264.  
  > **username_2**: Yes, actually it looks as if you can do it in one step: combine the video from the original MP4 and a new AAC/MP3 into a new MP4.  
  > **username_3**: You could endup with 2 audio stream though depending on how the original audio is mapped in the container and how ffmpeg handles this situation, it either creates a second audio stream or replaces the first when using -map 1.  
  
  ---
  
  