Students often encounter some problems in the process of learning the introduction to video course Small white system. Here are some of the most common problems for your reference:

Q: After ffmpeg is successfully compiled in Mac 10.15.3, a crash occurs when the ffmpeg command is run.

A: Recompile ffmpeg and add –extra-cflags=”fno-static-check” when executing./configure.

Q: Add –extra-cflags=”fno-static-check” option to still crash

A: Keep as few parameters as possible when compiling, should be in conflict with some other parameters

Q: Xcode compilation succeeds, but execution fails

A: When executing the course example, close the sandbox and add access to the MIC phone in the info.list.

Q: The program still cannot be executed after the sandbox is closed

A: Developer certification is required.

Q: After introducing ffMPEG library, report code signature… not valid

A:

1. Open keychain access. app on the Mac and choose My Certificate. 2. Perform codesign-f -s "Certificate Name"Xxx.dylib 3. To avoid signing one by one, coDesign can be done in batches-f -s "Certificate Name" /usr/local/ffmpeg/lib/*.dylib
Copy the code

Q: FfmPEG execution indicates that there is no permission

A: Switch to your own user directory and run FFmpeg.

The data in the virtual machine is very small, only 64 bytes, how to resampling?

A: The minimum number of samples in FFMPEG is 32, so there is no resampling when there is only 64 bytes of data. The solution is to put the data into a buffer, accumulate it to a certain size, and then resample it.

Q: Error -35 is returned when collecting body data from the device

A: Your device is not ready at the moment. You should wait A few seconds for it to read data normally.

Q: The encoder returns a -35 error while encoding

A: The encoder is not ready. Wait A few seconds.

Q: FfMPEG is compiled without FFplay

A:

/configure --enable-sdl2 3. Make && make installCopy the code

Q: The liBFDK-AAC library cannot be found when the collected audio data is encoded by AAC

A:

/configure and add --enable-fdk-aac 3. Make && make installCopy the code

Q: How to collect audio data in Linux

A: ffmpeg-f alsa -i hw:0,0 xxx.wav

Q: The ALSA device cannot be found in Linux

A: You can use arecord -l to see which audio devices you have under Linux. If alSA is not available, oss can be used.

Q: FfMPEG is compiled in Windows

A: trac.ffmpeg.org/wiki/Compil…

reference

Audio and video small white system introduction class