I have a video on my computer that was originally produced into wmv. I used VLC to convert it to mp4. I used both the "H.264+MP3 (MP4)" and the "Video for iPod HD" options. The audio clearly plays on my (Windows) computer. I then used whatsapp web to send it to a group chat. On my computer whatsapp web plays fine.
However in Whatsapp the audio doesn't come through. Even in the photos app, iOS shows a grayed out audio button.
Now to help isolate, I sent the file over Dropbox to my phone and it works within Dropbox. Which made me think its whatsapp. But when I save it to Photos, I'm back to same issue - so this leaves VLC not encoding something correctly or iOS not decoding something. I'm hoping someone can shine some light on why this is occurring.