FFMpeg使用常见的一些错误（Xcode9）

FFmpeg的编译就不说了，网上有很多的shell脚本，可以自己下载一个，根据自己的需求改一改。关于iOS编译FFmpeg库的脚本到GitHub上下载。脚本的地址：[https://github.com/kewlbear/FFmpeg-iOS-build-script]

在学习这个库的时候遇到的Xcode编译问题 （Xcode9.1）

• 问题1 因为导入系统库 Xcode9.1 不是自动帮你连接到项目中的，如果你导入.a库，在编译的时候，报如下的错误：

Undefined symbols for architecture arm64:
  "_iconv", referenced from:
      _avcodec_decode_subtitle2 in libavcodec.a(decode.o)
  "_iconv_open", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(decode.o)
  "_iconv_close", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(decode.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

错误素材1.jpg

解决办法，下图所示 👇

素材2.jpg

• 问题2 当使用av_register_all()函数的时候报了如下的错误：

Undefined symbols for architecture arm64:
  "_CMTimeMake", referenced from:
      _vtenc_send_frame in libavcodec.a(videotoolboxenc.o)
  "_kCMTimeInvalid", referenced from:
      _vtenc_send_frame in libavcodec.a(videotoolboxenc.o)
  "_CMSampleBufferGetSampleAttachmentsArray", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_kCMSampleAttachmentKey_NotSync", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_CMSampleBufferGetFormatDescription", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
      _vtenc_output_callback in libavcodec.a(videotoolboxenc.o)
  "_CMBlockBufferCopyDataBytes", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_CMVideoFormatDescriptionGetH264ParameterSetAtIndex", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
      _get_params_size in libavcodec.a(videotoolboxenc.o)
      _copy_param_sets in libavcodec.a(videotoolboxenc.o)
  "_CMSampleBufferGetPresentationTimeStamp", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_CMSampleBufferGetTotalSampleSize", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_CMBlockBufferCreateWithMemoryBlock", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_CMSampleBufferGetDataBuffer", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_kCMTimeIndefinite", referenced from:
      _vtenc_init in libavcodec.a(videotoolboxenc.o)
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
      _vtenc_close in libavcodec.a(videotoolboxenc.o)
  "_CMSampleBufferCreate", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms", referenced from:
      _videotoolbox_default_init in libavcodec.a(videotoolbox.o)
  "_CMSampleBufferGetDecodeTimeStamp", referenced from:
      _vtenc_frame in libavcodec.a(videotoolboxenc.o)
  "_CMVideoFormatDescriptionCreate", referenced from:
      _videotoolbox_default_init in libavcodec.a(videotoolbox.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

错误素材3.jpg

解决办法

• 第一：将报错信息里面的系统库 VideoToolbox.framework导入项目中，别忘了手动链接（Xcode9 不是自动帮你链接的，链接方法跟问题1的链接方法一样）
• 第二：在用到av_register_all()函数地方导入VideoToolbox.framework的头文件
• 注意：如果报错的信息是AudioToolbox... ，那么就需要导入AudioToolbox.framework , 导入#import<AudioToolbox/AudioToolbox.h>
  如下所示👇
  素材4.jpg

先记录这两个错误，之后遇到新的错误，继续追加🙂