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Transcoding & File Container


arche

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arche

Please excuse my ignorance towards this subject, but I am still fairly new to the home media subject. We have bought more chromecast devices for my house I am trying to understand why some movies require transcoding and some do not. Is there a better container to use versus others to keep the transcoding down? Hopefully someone can break this down for me when they have time. I would like to limit the amount of transcoding needed, so if someone can recommend what kind of settings I should use or software to convert my current files to the correct format.

 

I have read that chromecast prefers 720p over 1080p, but this just came up over random searches so I am not exactly sure how true this is.

 

Thanks for any help provided.

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Koleckai Silvestri

To prevent transcoding you want to use h.264 video and AAC 2-channel audio. If you use subtitles, the preferred format is srt. The container doesn't matter but the popular ones are MKV and MP4.

 

Bitrate is most likely going to be the cause of transcoding though. Most of the clients expect HD video to be at 3.2 megabits or less. At least on the default settings. You can adjust the client if your network allows for the higher bandwidth. If you're on cellular than you will want lower bitrates.

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The Baron

Howdy,

 

I believe, correct me if I am wrong, what will define if a movie is transcoded or not is the actual size of the file (movie) being played and the available bandwidth to send the movie to its destination.

 

This document, https://support.google.com/chromecast/answer/3272056?hl=en, references 3 available quality settings, 720p Extreme, 720p High, 480p Standard. Brilliantly, it does not define the bitrate, just the sizes of the 3 options. 

 

This below link gives the following speeds 5.0 Mbps for extreme (720p high bitrate), 3.0 Mbps for High (720p), 1.7 Mbps for Standard (480p) http://www.anandtech.com/show/7186/google-chromecast-review-an-awesome-35-hdmi-dongle/4

 

So, if you have a movie that was encoded at 1080p, then it will need to be transcoded to 720p to be able to be played via the Chromecast.

 

Also, depending on the setting you have (Extreme, High, Standard) a higher bit rate that 5, 3 or 1.7 Mbps respectively would need to be reduced to a workable size/rate to allow for Chromcast playback. 

 

I presume that is why transcoding is needed.

 

Hope you survived the tedium of my post to get something out of it, if I am not in fact way of the reserve on the matter of Chromecast/transcoding, here.

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arche

Thank you @ 

 

I do have another questions though, for AAC if it just says stereo is this considered 2-channel? Also, I tried using YAMB to convert a couple of files for testing, but did not help for the transcoding. Should I be using Handbrake or something else to convert these files? I only want to convert TV/Movies that I am really not concerned about having 5.1 audio and such.

 

Thank you again.

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arche

Thanks @@The Baron

 

I am really hoping they will support 1080p soon or if this is a hardware compatibility issue, then I will just have to deal with it. But what you have said, pretty much goes with the searching I have done. Just was not sure on the accuracy of the places I found the info.

Edited by nirvmedia
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Koleckai Silvestri

Stereo is 2 channels, left and right. Other formats will give a speaker count such as 2.1, 3.1, 5.1 and 7.1.

 

Handbrake will convert your video, allow you to reduce the bit rate and choose audio streams to keep. It is what I use if I need to convert something.

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thefirstofthe300

Just because I am a geek...FFMpeg for transcoding.  With it, I can do just about anything I want.  I am even starting to transcode new movies that I pickup using x265 with it. (I know that x265 is still far from finished, but I like saving the space.)  You can specify exactly how you want the output file to look.

 

If you want to look into it, the documentation is actually pretty good.  You will want to look at the -map option, the -codec option, and the -ac option.  Those will be the main things.

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