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Our client sent us a couple of videos files for audio transcription work. They said that we should use Player Microsoft application 4.8.0.0 to properly run the two files [right clicking these files, and going to their properties, shows the File Type as MP4 File (.mp4)].

We were so sure that VLC Media player could play any type of video, so without bothering to know what this Microsoft Application is, we tried to open those files through VLC. But to our surprise, the video part of the file played well in VLC, but the audio part was completely missing in the entire length of both the files.

Then we checked those files in Realplayer, Windows Media Player, a couple of other players, but the result was same - Video OK. Audio gone.

We checked those files in various desktop and laptop running different OS : Windows XP, Windows 7 and Windows 8. Result was same as above. Other video files, youtube.com etc. were playing completely ok - both video and audio - in all those media players we have in all the systems in our office.

Defeatedly, we googled for 'Player Microsoft application 4.8.0.0' but found no such software to download and try. Then the client gave us a setup file of another media player named flvplayer4free free flv player setup. We also found the same piece of software at this link. However, to much of our disappointment, both copies of the setup, one given by the client and another download from the link, refused to be installed on any of the systems with various OS we have. After initially running for a couple of seconds while being installed, this software always flashed a message box saying : 'I have some issues starting up, please launch me again!'

The client said it is not their headache how we run those videos as those were running ok at their site. We either figure it out ourselves or we loose the job, client, contract & security money.

After a little more search and hit-&-trial, we found that the video was running WITH audio as desired when we transferred them to our Android mobile phone. The audio was clearly audible and the file was being run through MX Media Player in the mobile. However, unfortunately, MX Media Player is not available for Windows but one thing we now were sure that the client is not telling a lie :) and the video file indeed has a working audible part in it, it is just somehow not working in any of our systems in any of the media player we tried so far.

Then we tried to find the solution in the cloud. We uploaded the videos both on Google Drive (Drive has a inbuilt media player) and Youtube.com. However, the result was still the same. Video OK. Audio gone.

We searched more and more and after a couple of days and many media player trials, we got our hand on SM Player - free and available here for download. This media player solved our problem as it is running both audio & video part properly & entirely.

So my question is :

1) why does it happen? what is so unique about a video that only a particular media player could play in entirety and other so popular media players failed to do so.

And my second question is more grave and forced me write this entire post :

2) When I cut the video in two parts (required due to some reason) through a software named Free Video Cutter, now even SM Player is refusing to play the parts with audio, whereas it plays the original video fine. Video is just cut into two parts being in the same format, so what happened to even to SM Player now?

Thanks for reading this long post, and I would heartily thankful to those who could guide me in the right direction for the issues I am facing.


Note: As suggested by @BrunoPereira, I have copy-pasted MediaInfo information of my video file below:

General
CompleteName                             : C:\Users\Vivek Raj\Desktop\client\work 2\ch01_20130509100300.mp4
Format                                   : MPEG-PS
FileSize/String                          : 1 017 MiB
Duration/String                          : 1h 16mn
OverallBitRate/String                    : 1 847 Kbps

Video
ID/String                                : 224 (0xE0)
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format_Profile                           : Main@L3.0
Format_Settings_CABAC/String             : No
Format_Settings_RefFrames/String         : 2 frames
Format_Settings_GOP                      : M=1, N=25
Duration/String                          : 1h 16mn
Width/String                             : 704 pixels
Height/String                            : 576 pixels
DisplayAspectRatio/String                : 1.222
FrameRate/String                         : 25.000 fps
Standard                                 : PAL
ColorSpace                               : YUV
ChromaSubsampling                        : 4:2:0
BitDepth/String                          : 8 bits
ScanType/String                          : Interlaced
ScanOrder/String                         : Top Field First

Audio
ID/String                                : 192 (0xC0)
Format                                   : MPEG Audio
Duration/String                          : 1h 16mn
Compression_Mode/String                  : Lossy
Video_Delay/String                       : 73ms
share|improve this question
    
There is a small utility called Mediainfo (mediainfo.sourceforge.net/en) that can display all the required information of a video file (video and audio types), use it to analyze the files sent to you and give us the information about the type of encoding used on them, it will make it easier to troubleshoot this problem you are having. –  Bruno Pereira May 28 '13 at 11:03
    
Thanks Bruno for your quick response! I downloaded and installed the Mediainfo from the link you gave. I hope you are looking for these info : –  VivR May 28 '13 at 11:40
    
i pasted at this google doc file : goo.gl/AqUWn –  VivR May 28 '13 at 11:50
    
Is that the complete output from MediaInfo? Somehow the Audio section looks incomplete. –  Karan May 28 '13 at 15:36
    
In SMPlayer press "Ctrl+I" to see file properties, and see which codec SMPlayer use to decode the audio (Initial Audio Stream - Selected Codec". Edit: Worst case scenario, you could record the audio through a loopback device, split it separatly from the video then join them again. –  Martin May 28 '13 at 16:03
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1 Answer 1

MP4 is just a file format. It describes how data is packed into a file, but doesn't tell you how it's been compressed. Your file uses video codec that is supported by your players and an audio codec which is not. Your players can't decode sound. That's also the reason why you don't hear sound after splitting the file - the program you used didn't support that codec, so it has just ommited sound entirely.

As @BrunoPereira suggested in the comments, you can use MediaInfo to get some details about the codec used.

share|improve this answer
    
Hi Gronostaj! Thanks for your reply! The Mediainfo details i have copy-pasted at this google doc file : goo.gl/AqUWn Look forward to listen from you. –  VivR May 28 '13 at 11:51
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