Recherche avancée

Sur d’autres sites (7850)

• How can I concat one single mp3 file many times (crossfades included) using ffmpeg ?

  16 avril 2021, par martijn

  I try to make a bash file with (an) ffmpeg command(s) in which a single mp3 file (let's say of two minutes duration) will be extended to for example 8 hours duration. Since mp3 files always have these gaps of silence at the front and back in order to make it seamless loops I need to use crossfading. How can I do this without having an enormous large command like :

  


  ffmpeg -i same.mp3 -i same.mp3 -i same.mp3 ....(hundreds of times)
-filter_complex "[0][1]acrossfade=d=5:c1=exp:c2=exp[a01] ...
etc (hundreds of times)
output.mp3

  


• x86inc : Prefer r14/r15 over r12/r13 on x86-64

  22 avril 2017, par Henrik Gramner

  x86inc : Prefer r14/r15 over r12/r13 on x86-64
  Due to a peculiarity in the ModR/M addressing encoding, the r12 and r13
  
  registers sometimes requires an additional byte when used as a base register.
  r14 and r15 doesn't have that issue, so prefer using them.
  

  • [DH] libavutil/x86/x86inc.asm

• ‘undefined reference to xxxxx’ , 'check the directory for the files' it does not work

  26 décembre 2011, par sirupa

  Merry Christmas, everybody,

  I’m coding ffmpeg with gcc.

  But, on the build process, I met the errors of ‘undefined reference to xxxxx’ for all functions that I coded in my program, and I recognized that it was due to the libxxx.a file.

  And the every adviser on internet suggested that check the directory for the files.

  So, I searched the files in which include the function names in my computer, and I found the .a files are correctly set in the directory which I coded.

  And there are the other files which are named ‘libxxx.dll.a’, so I tried to build with the files ‘libxxx.dll.a’, but I got the same result.

  On this point, I have got some questions.

  1) If the gcc could not find the libxxx.a files, it would say that ‘cannot find the –lxxx’. But it just said ‘undefined reference to xxxx’. It means that those libxxx.a files are in the correct directories.

  2) And if the files do not define the functions, it is strange. Because those files include the function names and are the same files/directories I had searched in my computer, and I think it should have the definitions of the functions. But I am not sure that the files define the functions or not, because I cannot read the file myself.

  If I am wrong, what was my mistake ?

  3) Can libxxxlib.a files be replaced with the libxxx.a ? And if it can, what is the difference between libxxxlib.a and libxxx.a ? And the same for the libz and libzlib ?a

  Here is my line commend, the directory which include the libxxx.a files.

  g++ -o C :\ffmpeg\ffmpegTest C :\ffmpeg\ffmpegTest.cc -IC :\ffmpeg -LC :\ffmpeg\3rdparty\lib -lavutil -lavformat -lavcodec -lz -lavutil -lm -D__STDC_CONSTANT_MACROS

  C :\ffmpeg\3rdparty\lib

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0xec> : undefined reference to 'av_register_all()'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x11c> : undefined reference to 'av_open_input_file(AVFormatContext*, char const, AVInputFormat*, int, AVFormatParameters*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x13b> : undefined reference to 'av_find_stream_info(AVFormatContext*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x174> : undefined reference to 'dump_format(AVFormatContext, int, char const*, int)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x224> : undefined reference to 'avcodec_find_decoder(CodecID)'

  and all the errors are

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x281> : undefined reference to 'avcodec_open(AVCodecContext*, AVCodec)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x297> : undefined reference to 'avcodec_alloc_frame()'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x2a3> : undefined reference to 'avcodec_alloc_frame()'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x2e6> : undefined reference to 'avpicture_get_size(PixelFormat,int,int)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x2fc> : undefined reference to 'av_malloc(unsigned int)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x341> : undefined reference to 'avpicture_fill(AVPicture*, unsigned char*, PixelFormat, int, int)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x38c> : undefined reference to 'avcodec_decode_video2(AVCodecContext, AVFrame*, int, AVPacket*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x409> : undefined reference to 'sws_getContext(int, int, PixelFormat, int, int, PixelFormat, int, SwsFilter*, swsFilter*, double const*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x463> : undefined reference to 'sws_scale(SwsContext*, unsigned char const* const*, int const*, int, int, unsigned char* const*, int const*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x4bb> : undefined reference to 'av_free_packet(AVPacket*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x4cf> : undefined reference to 'av_read_frame(AVFormatContext, AVPacket*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x36c> : undefined reference to 'av_free(void*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x36c> : undefined reference to ' avcodec_close(AVCodecContext*)'

  C :\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc :<.text+0x36c> : undefined reference to 'av_close_input_file(AVFormatContext)'