How can I find out what this ffmpeg error code means?

Question

I am using the avcodec_decode_video2 function. When changing the encoding in the stream, it returns -1094995529. The documentation only states:

On error, a negative value is returned, otherwise the number of bytes is used, or zero if the frame cannot be decompressed.

But there seems to be no enumeration of return codes or any other form of documentation. What does the error mean and how can I determine it at all?

Answer 1

Error codes from ffmpeg (error.h from avutil): http://ffmpeg.org/doxygen/trunk/error_8h_source.html

It turned out that the value you specified:

#define AVERROR_INVALIDDATA FFERRTAG( 'I','N','D','A') 

-1094995529 becomes -0x41444E49, and when you look at these letters, in ACSII, 0x41 = 'A', 0x44 = 'D', 0x4E = 'N and 0x49 =' me '. Because the / etc macro has changed, so ADNI becomes INDA, which you can see from the #define snippet is AVERROR_INVALIDDATA defined by FFERRTAG ('I', 'N', 'D', 'A').

The remaining error codes are in this file, and I inserted them below:

 #define AVERROR_BSF_NOT_FOUND FFERRTAG(0xF8,'B','S','F') ///< Bitstream filter not found #define AVERROR_BUG FFERRTAG( 'B','U','G','!') ///< Internal bug, also see AVERROR_BUG2 #define AVERROR_BUFFER_TOO_SMALL FFERRTAG( 'B','U','F','S') ///< Buffer too small #define AVERROR_DECODER_NOT_FOUND FFERRTAG(0xF8,'D','E','C') ///< Decoder not found #define AVERROR_DEMUXER_NOT_FOUND FFERRTAG(0xF8,'D','E','M') ///< Demuxer not found #define AVERROR_ENCODER_NOT_FOUND FFERRTAG(0xF8,'E','N','C') ///< Encoder not found #define AVERROR_EOF FFERRTAG( 'E','O','F',' ') ///< End of file #define AVERROR_EXIT FFERRTAG( 'E','X','I','T') ///< Immediate exit was requested; the called function should not be restarted #define AVERROR_EXTERNAL FFERRTAG( 'E','X','T',' ') ///< Generic error in an external library #define AVERROR_FILTER_NOT_FOUND FFERRTAG(0xF8,'F','I','L') ///< Filter not found #define AVERROR_INVALIDDATA FFERRTAG( 'I','N','D','A') ///< Invalid data found when processing input #define AVERROR_MUXER_NOT_FOUND FFERRTAG(0xF8,'M','U','X') ///< Muxer not found #define AVERROR_OPTION_NOT_FOUND FFERRTAG(0xF8,'O','P','T') ///< Option not found #define AVERROR_PATCHWELCOME FFERRTAG( 'P','A','W','E') ///< Not yet implemented in FFmpeg, patches welcome #define AVERROR_PROTOCOL_NOT_FOUND FFERRTAG(0xF8,'P','R','O') ///< Protocol not found #define AVERROR_STREAM_NOT_FOUND FFERRTAG(0xF8,'S','T','R') ///< Stream not found #define AVERROR_BUG2 FFERRTAG( 'B','U','G',' ') #define AVERROR_UNKNOWN FFERRTAG( 'U','N','K','N') ///< Unknown error, typically from an external library #define AVERROR_EXPERIMENTAL (-0x2bb2afa8) ///< Requested feature is flagged experimental. Set strict_std_compliance if you really want to use it. #define AVERROR_INPUT_CHANGED (-0x636e6701) ///< Input changed between calls. Reconfiguration is required. (can be OR-ed with AVERROR_OUTPUT_CHANGED) #define AVERROR_OUTPUT_CHANGED (-0x636e6702) ///< Output changed between calls. Reconfiguration is required. (can be OR-ed with AVERROR_INPUT_CHANGED) #define AVERROR_HTTP_BAD_REQUEST FFERRTAG(0xF8,'4','0','0') #define AVERROR_HTTP_UNAUTHORIZED FFERRTAG(0xF8,'4','0','1') #define AVERROR_HTTP_FORBIDDEN FFERRTAG(0xF8,'4','0','3') #define AVERROR_HTTP_NOT_FOUND FFERRTAG(0xF8,'4','0','4') #define AVERROR_HTTP_OTHER_4XX FFERRTAG(0xF8,'4','X','X') #define AVERROR_HTTP_SERVER_ERROR FFERRTAG(0xF8,'5','X','X') 

Answer 2

The indicated errors relate to POSIX:

in the file libavcodec \ avcodec.h

 #include <errno.h> #if EINVAL > 0 #define AVERROR(e) (-(e)) /**< Returns a negative error code from a POSIX error code, to return from library functions. */ #define AVUNERROR(e) (-(e)) /**< Returns a POSIX error code from a library function error return value. */ #else /* Some platforms have E* and errno already negated. */ #define AVERROR(e) (e) #define AVUNERROR(e) (e) #endif #define AVERROR_UNKNOWN AVERROR(EINVAL) /**< unknown error */ #define AVERROR_IO AVERROR(EIO) /**< I/O error */ #define AVERROR_NUMEXPECTED AVERROR(EDOM) /**< Number syntax expected in filename. */ #define AVERROR_INVALIDDATA AVERROR(EINVAL) /**< invalid data found */ #define AVERROR_NOMEM AVERROR(ENOMEM) /**< not enough memory */ #define AVERROR_NOFMT AVERROR(EILSEQ) /**< unknown format */ #define AVERROR_NOTSUPP AVERROR(ENOSYS) /**< Operation not supported. */ #define AVERROR_NOENT AVERROR(ENOENT) /**< No such file or directory. */ #define AVERROR_EOF AVERROR(EPIPE) /**< End of file. */ #define AVERROR_PATCHWELCOME -MKTAG('P','A','W','E') /**< Not yet implemented in FFmpeg. Patches welcome. */ 

This is a complete set of Errors that you may encounter. Just inside the code, check the return value for all of them.