Author Topic: Iphone devices play mp4 converted videos with no sound  (Read 195 times)

erkan_iii

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Iphone devices play mp4 converted videos with no sound
« on: March 29, 2020, 11:36:22 PM »
Hi there

I have no idea about techniqal jargon. I Just use the software.

I convert some mkv videos to mp4 using avidmux 2.7.5. The end product does play well with sound but not in iphone devices. The video plays well but there is no sound. when I convert I choose the following options: mpeg4 avc x264 as video output, mp3 lame as audio output. and mp4 muxer. I have no idea what the other options are or what do they do.

Can you help me please fix this problem

thank

Erkan

eumagga0x2a

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Re: Iphone devices play mp4 converted videos with no sound
« Reply #1 on: March 29, 2020, 11:45:46 PM »
You should use AAC for audio track. Avidemux has a number of AAC encoders, any of them will do.

For anything mp4 related you might want to use the latest Avidemux nightly rather than earlier versions like the last release.

https://avidemux.org/nightly/vsWin64/
« Last Edit: March 29, 2020, 11:48:04 PM by eumagga0x2a »

erkan_iii

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Re: Iphone devices play mp4 converted videos with no sound
« Reply #2 on: March 30, 2020, 02:32:54 PM »
Hi eumagga0x2a

Thanks you for the prompt answer and generous help. ACC Helped to solve the problem.

If I may ask, Is there any software that can cut video between the keyframes without rendering the video.

I have been using losslesscut.exe to cut and merge videos without rendering. It is fast and efficient. The only problem is when i cut between key frames it will not play the video only Audio would play until the next keyframe where it start to show video.

can i cut between the keyframe using avidemux without rendering and without experiencing such problem.

Any further information in this regards would be appreciated.

Thanks again

Erkan

eumagga0x2a

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Re: Iphone devices play mp4 converted videos with no sound
« Reply #3 on: March 30, 2020, 03:05:37 PM »
Is there any software that can cut video between the keyframes without rendering the video.

In general, this is impossible without re-encoding at least a part of the video due to the very nature of video compression.

Now let's go into detail.

Not all keyframes are equal. All keyframes can act as a seek point, i.e. frames which allow to start playback without any broken, pixelated pictures spoiling the show. But only so-called IDR (instantaneous decoder refresh) keyframes allow to make a clean cut in a sense that no single frame following such a keyframe may depend on any frame preceding the IDR frame in stream order (you should know that in modern codecs like H.264 and HEVC, the display order of decoded pictures may be different from their order in the data stream).

The fundamental feasibility of such a feature requires that

1. the keyframe following the cut point is an IDR and...

2. ...we can re-encode the part of the GOP after the cut point with exactly the same decoder parameter sets (the information which is supplied along the compressed image data and tells the decoder how to interpret this information) as used by the source video.

The second point is very difficult to achieve (it is very difficult to find a matching encoder configuration), the first one depends on the particular sort of stream you've got to edit. Many sources like digital television insert very few IDR frames into their streams, almost all keyframes are just seek points which doesn't allow a clean cut.

Avidemux doesn't support such "smart copy". Even if it would, the success would greatly depend on the particular source video and thus cause a lot of confusion.