user16374: I have several media:

one video file
several audio files

I would like to create a new MXF media with the video file and mixing the audio files at specific timestamp and tracks:

Starting time of the video file on the track 0: 00:00:00:00
Starting time of the audio clip 1 on the track 1: 00:00:30:00
Starting time of the audio clip 2 on the track 2: 00:00:35:00
Starting time of the audio clip 3 on the track 2: 00:00:45:00
...

I made a first try with just with one video and one audio. I used the following command:
ffmpeg -y -i picsou.mp4 \
  -itsoffset 2 \
  -i picsou.wav \
  -shortest \
  out.mp4

Unfortunately, when I import it in Pro Tools, I cannot see the audio.

user1871: The method in my comment still stands.
Let's say you have two audio tracks. Basic command syntax is
ffmpeg -i picsou.mp4 \
       -i audio1.wav \
       -i audio2.wav \
       - filter_complex "[1:a]adelay=30000|30000[1a];\
                         [2:a]adelay=35000|35000[2a]" \
      -map 0:v -map "[1a]" -map "[2a]" -c:v copy -shortest \
  out.mxf

The adelay filter here expects two channels per input stream. Channel delay values are in milliseconds.
On linux / OSX you may have to use single quotes around the arguments.

16374: <p>I have several media:</p>

<ul>
<li>one video file</li>
<li>several audio files</li>
</ul>

<p>I would like to create a new MXF media with the video file and mixing the audio files at specific timestamp and tracks:</p>

<ul>
<li>Starting time of the video file on the track 0: <code>00:00:00:00</code></li>
<li>Starting time of the audio clip 1 on the track 1: <code>00:00:30:00</code></li>
<li>Starting time of the audio clip 2 on the track 2: <code>00:00:35:00</code></li>
<li>Starting time of the audio clip 3 on the track 2: <code>00:00:45:00</code></li>
<li>...</li>
</ul>

<p>I made a first try with just with one video and one audio. I used the following command:</p>

<pre><code>ffmpeg -y -i picsou.mp4 \
  -itsoffset 2 \
  -i picsou.wav \
  -shortest \
  out.mp4
</code></pre>

<p>Unfortunately, when I import it in <em>Pro Tools</em>, I cannot see the audio.</p>
 1871: <p>The method in my comment still stands.</p>

<p>Let's say you have two audio tracks. Basic command syntax is</p>

<pre><code>ffmpeg -i picsou.mp4 \
       -i audio1.wav \
       -i audio2.wav \
       - filter_complex "[1:a]adelay=30000|30000[1a];\
                         [2:a]adelay=35000|35000[2a]" \
      -map 0:v -map "[1a]" -map "[2a]" -c:v copy -shortest \
  out.mxf
</code></pre>

<p>The adelay filter here expects two channels per input stream. Channel delay values are in milliseconds.</p>

<p>On linux / OSX you may have to use single quotes around the arguments.</p>
