Revert "docs: remove every ffmpeg mention in the documentation to avoid confusion"

This reverts commit 1e05bbce03.

docs/en/README.en.md

@@ -128,7 +128,26 @@ If you want to use the v2 version of the model, you need to download additional
 	rvcmd assets/v2 # RVC-Models-Downloader command
 	```
 
-### 2. Download the required files for the rmvpe vocal pitch extraction algorithm
+### 2. Install ffmpeg tool
+If `ffmpeg` and `ffprobe` have already been installed, you can skip this step.
+#### Ubuntu/Debian
+```bash
+sudo apt install ffmpeg
+```
+#### MacOS
+```bash
+brew install ffmpeg
+```
+#### Windows
+After downloading, place it in the root directory.
+```bash
+rvcmd tools/ffmpeg # RVC-Models-Downloader command
+```
+- [ffmpeg.exe](https://huggingface.co/lj1995/VoiceConversionWebUI/blob/main/ffmpeg.exe)
+
+- [ffprobe.exe](https://huggingface.co/lj1995/VoiceConversionWebUI/blob/main/ffprobe.exe)
+
+### 3. Download the required files for the rmvpe vocal pitch extraction algorithm
 
 If you want to use the latest RMVPE vocal pitch extraction algorithm, you need to download the pitch extraction model parameters and place them in `assets/rmvpe`.
 
@@ -144,7 +163,7 @@ If you want to use the latest RMVPE vocal pitch extraction algorithm, you need t
 	rvcmd assets/rmvpe # RVC-Models-Downloader command
 	```
 
-### 3. AMD ROCM (optional, Linux only)
+### 4. AMD ROCM (optional, Linux only)
 
 If you want to run RVC on a Linux system based on AMD's ROCM technology, please first install the required drivers [here](https://rocm.docs.amd.com/en/latest/deploy/linux/os-native/install.html).
 
@@ -188,6 +207,7 @@ rvcmd packs/general/latest # RVC-Models-Downloader command
 + [VITS](https://github.com/jaywalnut310/vits)
 + [HIFIGAN](https://github.com/jik876/hifi-gan)
 + [Gradio](https://github.com/gradio-app/gradio)
++ [FFmpeg](https://github.com/FFmpeg/FFmpeg)
 + [Ultimate Vocal Remover](https://github.com/Anjok07/ultimatevocalremovergui)
 + [audio-slicer](https://github.com/openvpi/audio-slicer)
 + [Vocal pitch extraction:RMVPE](https://github.com/Dream-High/RMVPE)

docs/en/faq_en.md

@@ -1,3 +1,8 @@
+## Q1:ffmpeg error/utf8 error.
+It is most likely not a FFmpeg issue, but rather an audio path issue;
+
+FFmpeg may encounter an error when reading paths containing special characters like spaces and (), which may cause an FFmpeg error; and when the training set's audio contains Chinese paths, writing it into filelist.txt may cause a utf8 error.<br>
+
 ## Q2:Cannot find index file after "One-click Training".
 If it displays "Training is done. The program is closed," then the model has been trained successfully, and the subsequent errors are fake;
 

docs/en/training_tips_en.md

@@ -20,6 +20,9 @@ Loads and preprocesses audio.
 If you specify a folder with audio, the audio files in that folder will be read automatically.
 For example, if you specify `C:Users\hoge\voices`, `C:Users\hoge\voices\voice.mp3` will be loaded, but `C:Users\hoge\voices\dir\voice.mp3` will Not loaded.
 
+Since ffmpeg is used internally for reading audio, if the extension is supported by ffmpeg, it will be read automatically.
+After converting to int16 with ffmpeg, convert to float32 and normalize between -1 to 1.
+
 ### denoising
 The audio is smoothed by scipy's filtfilt.