I am a big fan of Google's Chromecast. I really like having a dumb device attached to an unfortunately not dumb TV that is entirely controlled via a smart phone. It keeps the number of remotes to a minimum, and it allows anyone on your network to easily watch their own content. I rarely have troubles casting to a Chromecast except when using particular mobile apps that do not implement the Chromecast APIs properly.
However, recently I encountered a new problem. When casting to a first generation Chromecast attached to a Sharp LC-40N5000U smart TV from Google Play, Vudu, or Netflix, the audio was high pitched and distorted. The internal TV speakers were being used to output audio.
While I have only used Chromecasts on a handful of TVs, this is the first TV where I have encountered this problem. Google searching for similar problems only turns up a handful of similar reports from 2014, but there is a post on the Chromecast Support Forums with the same problem on the same TV model.
I thought the first generation Chromecast might be the cause of the problem, but, when I attached a second generation Chromecast, the high pitched and distorted audio remained.
I tried different HDMI ports. I looked through and tried changing the TV's audio settings. I removed the HDMI extension cable attached to the first generation Chromecast. I made sure the TV had up-to-date firmware. But, no matter what, the issue remained.
Additionally, the issue occurred regardless if using Google Play, Vudu, or Netflix on Android or iOS. However, seemingly random movies and TV shows on Netflix did not exhibit the problem, and casting from YouTube - I only tried one or two videos - had no issues either.
So, what was causing the problem? The TV? The Chromecast?
I finally zeroed in on the problem when casting from the Movies Anywhere Android app.
The Movies Anywhere app allows you to select an audio stream: stereo (2.0) or surround sound (5.1). Most movies will default to streaming using surround sound. The moment I manually changed the audio stream to stereo, the TV played the audio properly. For whatever reason, this particular TV model was not capable of downsampling the surround sound audio to stereo. This explains why some movies and TV shows casted from Netflix did not exhibit the problem; those video streams must only have stereo audio streams.
Ironically, the Vudu and Netflix apps installed on the smart TV did not exhibit any high pitched or distorted audio, so they are either downsampling surround sound to stereo properly or only play stereo audio. Because of that, I can't entirely blame the TV, and I can't entirely blame the Chromecast for this issue. It must be some sort of incompatibility between both of them. Perhaps there is an issue with surround sound audio coming through an HDMI port. I really don't know.
If you encounter this issue on a different TV model, try using the Movies Anywhere mobile app or figuring out if whatever mobile app you are casting from allows you to select stereo sound.