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Why Sometimes QuickTime Can't Play MP4 Files

As one of the most popular default media player on Mac, QuickTime is able to provide users with various video formats playback solutions with the best audio and picture quality. However, QuickTime is not compatible with all video formats all the time. For example, MP4 can’t be recognized and played in QuickTime at times. This is an annoying problem for many users because MP4 format is widely used over the Internet and a lot of files are formatted in MP4 nowadays. Are there any ways to figure out the problem? If QuickTime won’t play MP4 files, are there any alternatives that you can refer to? In this article, all the questions will be answered properly.

Part 1: Can QuickTime Play MP4 Files

Can QuickTime play MP4 files? Actually, according to the Apply website, QuickTime player does really support MPEG-4 which includes MP4 and M4V formats, which means QuickTime can play MP4 files corrects sometimes. However, at times, QuickTime can’t open MP4 due to the variety of the MP4 codec. Before we start to figure out all the questions, we had better get to know the exact meaning of MP4 format and the QuickTime.

MP4 was originally an audio format and has little to do with MPEG-4, just as MP3 and MPEG-3 have nothing to do with it. MP3 is an abbreviation of MPEG-1 Audio Layer 3; MP4 is MPEG-2 AAC, which is completely an audio compression format. Different coding algorithms of MP4 format can be used for different objects, thereby further improving compression efficiency. The objects are relatively independent, which improves the reusability of multimedia data. MP4 container video format allows users to operate on a single object, providing unprecedented interactivity. Simply speaking, commonly MP4 is video format that has various audio and video codec.

What is QuickTime player really is? Why sometimes QuickTime won’t open MP4? QuickTime is a built-in media player with powerful multimedia technology that allows you to watch Internet videos, HD movie trailers and personal media works in a variety of file formats, giving you an exceptionally high quality. As a powerful audio and video player from Apple that listens to/watches the web, QuickTime 3.0 can also handle still images, animated images, vector graphics, multi-track, MIDI music, 3D, virtual reality panoramas and virtual reality objects, and of course text.

Above all, the exact reason for the failure of playing MP4 files in QuickTime should lie in that some MP4 codecs are missing in the player. With other words, if the QuickTime misses a kind of audio or video codecs of MP4, then it will result in that QuickTime won’t play MP4 files.


Part 2: How to Play MP4 Files in QuickTime When It Can't Play the MP4 Files

Since the missing of proper MP4 codec is the main reason for the failure, then in order to solve the problem correctly, you should focus on the MP4 codec. Codec is used to support video and audio compression (CO) and decompression (DEC) codecs or software. Codec technology can effectively reduce the space occupied by digital storage and improve system operation efficiency. Codec encodes and compresses the transmission of the AD-converted audio and video digital signals, and decodes the signals at the receiving end which are commonly used in video conferencing, streaming media, video applications and other occasions. In order to play MP4 files correctly, you must make sure that the MP4 codec has been fully contained in the QuickTime. Therefore, you can follow the several steps below to play MP4 file in QuickTime player.

Step 1: Have a full check on QuickTime player. You need to check whether there are any other reasons that result in the failure of playing MP4 in QuickTime. For example, make sure QuickTime has been updated to the latest version. Additionally, check that whether the MP4 files are all in the good conditions without any damage.

Step 2:
Locate the MP4 codec. If all other conditions have been check and both the MP4 files and QuickTime are all in good conditions, then another major reason that QuickTime won’t open MP4 files is the lack of MP4 codec. Next, what you need to do is to search for MP4 codec over the Internet. There are a lot of MP4 codec to be downloaded from the Internet. Here I will strongly recommend you to download and install the several MP4 codec for QuickTime below.

No. 1 Perian

As a QuickTime MP4 codec, Perian is able to help you play videos and audios that are not compatible now, including MP4 and so on. This MP4 codec supports a variety of multimedia files. When the codec has been downloaded and installed on your computer, then you will be able to play many videos, including AVI, DixX, MKV and so on.


No. 2 K-Lite Codec Pack

K-Lite Codec Pack is one of the most popular codecs to encode various audios and videos. It includes all the multimedia files playback solutions and can meet your general requirement in most players. Here, MP4 codec can be easily found within K-Lite Codec Pack. It is quite easy to download and install, at the same time, it is less space-consuming on your computer.


You can choose from the two of the MP4 codecs based on your own preferences and needs. The installation process is quite simple. First of all, download the codec pack over the Internet. Once it has been downloaded, then you should unzip the file and follow the installation steps shown on the screen to complete the process. When the codec has been fully installed on your computer, what you need to do is to restart QuickTime and try to load the MP4 files once again. Then you can easily play and open the MP4 files in QuickTime.

Part 3: How to Convert MP4 Files to QuickTime Format - Leawo Video Converter

Asides from downloading and installing the MP4 codec for QuickTime, another efficient way to enable QuickTime to play MP4 files is to convert the MP4 format to another QuickTime-compatible format, such as MOV and so on. The necessary thing you should do is to seek help from an excellent video converter which has the capability to convert MP4 to MOV or other QuickTime-compatible formats. Concerning the top video converters, Leawo Video Converter will have to be included on your list. With Leawo Video Converter, you can easily convert your targeted video formats to other more than 180 types of video formats without any quality loss. During the converting process, you are allowed to set the various audio and video parameters so as to obtain the best and personalized videos, such as trimming, cropping, 3D effects adding, subtitles adding, and watermark adding and so on. For the details, please refer to the following steps.

Step 1: Download Leawo Video Converter and install it on your computer.


Step 2:  Add the MP4 video to the converter. When you open the converter, just click on the “Add Video” icon to import the file to the program.

Leawo-Video-Converter 1

Step 3: Confirm the output format. Go to open drop-down box beside the green icon “Convert” to choose “Change” to enter the “Profile” panel, then you can see a lot of output video formats, including MOV, MPEG, AVI and so on. MOV is perfectly compatible with QuickTime, so, you can set MOV as the output format (based on your own needs).

Leawo-Video-Converter 2

Step 4: Set the HD Video parameters. You can set the “Video Codec”, “Bite Rates”, “Resolution”, “Frame Rate” and “Aspect Ratio” parameters accordingly.

Leawo-Video-Converter 3

Step 5: Start converting MP4 to MOV. Click the big green icon “Convert” on the main interface to start converting the MTS file to HD MP4. Then, confirm the “Save to” route and click “Convert” to start. Last, you only need to wait patiently, the conversion process will usually last minutes.

Leawo-Video-Converter 4

Part 4: Another Alternative MP4 Player on Mac - Leawo Blu-ray Player

Additionally, there is another way for your further reference to play MP4 file correctly on Mac. Are there any powerful media players on Mac that can support MP4 video playback without any problems? The answer is positive. Leawo Blu-ray Player for Mac is a very good option to be used as the MP4 player. You can easily obtain all kinds of video playbacks in more than 180 types of formats with ease and accuracy with Leawo Blu-ray Player. It can allow user to enjoy various commercial DVD and Blu-ray discs with region code protection. Furthermore, its bonus features including virtual remote controller, screen shot functions and various audio and video settings make this player much more comprehensive and attractive.  

Part 5: Conclusion

QuickTime can sometimes play MP4 files without any codec error, while some issues may still happen during the playback. The direct way is to install the MP4 codec for QuickTime or convert the MP4 format to another QuickTime-compatible format. Alternatively, you can also try to play MP4 files with Leawo Blu-ray Player.



With long-term dedication into the latest market demands and technologies, the author has become an expert in posting practical, in-depth and user-oriented how-tos, tutorials, recommendations, reviews, and more digital multimedia solutions in Blu-ray, DVD, video, audio, picture, Apple utilities, etc.

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