user2059: I have a video (from my Android Nexus One).  Dimensions are 720 x 480.
The pixel aspect ratio is, according to data embedded in the file, 0.9091.
Now, editing the video and exporting it to a media that says it has square pixel obviously makes the video look 'narrow' on the X axis.
The only way I could edit this in Premiere and export it to MPEG (2 or 4), was to scale each source video up to 109.9% on the X axis (since 0.9091 * 1.09 is ca 1.0).  Premiere doesn't allow me to say that the generated file as a pixel aspect ratio of 0.9091.
This works, but feels wrong.  Especially if I have lots of source videos, to set the scaling factor on each of them.
Is there a better way to do this ?

user1871: If you're exporting directly from Premiere, then select the MPEG2-DVD NTSC preset in File -> Export -> Media, as shown in this image. 
Also, it looks like MP4Box will allow you to change the pixel aspect ratio flag in a .mp4 without re-encode.
FYI: 720x480 with PAR 0.9091 @ 29.97fps is the NTSC DV standard resulting in a 4:3 display aspect ratio. Similarly, 720x576 with PAR 1.0667* @ 25fps is the PAL DV standard.
*The actual PAR is supposed to be 59/54, but many apps use 16/15. See here if you're interested.

2059: <p>I have a video (from my Android Nexus One).  Dimensions are 720 x 480.
The pixel aspect ratio is, according to data embedded in the file, 0.9091.</p>

<p>Now, editing the video and exporting it to a media that says it has square pixel obviously makes the video look 'narrow' on the X axis.</p>

<p>The only way I could edit this in Premiere and export it to MPEG (2 or 4), was to scale each source video up to 109.9% on the X axis (since 0.9091 * 1.09 is ca 1.0).  Premiere doesn't allow me to say that the generated file as a pixel aspect ratio of 0.9091.</p>

<p>This works, but feels wrong.  Especially if I have lots of source videos, to set the scaling factor on each of them.</p>

<p>Is there a better way to do this ?</p>
 1871: <p>If you're exporting directly from Premiere, then select the MPEG2-DVD NTSC preset in File -> Export -> Media, as shown in this <a href="http://i1.creativecow.net/u/205208/mpeg2-dvd_settings.png" rel="nofollow">image</a>. </p>

<p>Also, it looks like MP4Box will allow you to change the pixel aspect ratio flag in a .mp4 without re-encode.</p>

<p>FYI: 720x480 with PAR 0.9091 @ 29.97fps is the NTSC DV standard resulting in a 4:3 display aspect ratio. Similarly, 720x576 with PAR 1.0667* @ 25fps is the PAL DV standard.</p>

<p>*<sub>The actual PAR is supposed to be 59/54, but many apps use 16/15. See <a href="http://www.mikeafford.com/blog/2009/03/pal-d1-dv-widescreen-square-pixel-settings-in-after-effects-cs4-vs-cs3/" rel="nofollow">here</a> if you're interested.</sub></p>
