Search code examples
c++ffmpeg

How can I found FFmpeg Error code's meaning?

I have an issue using FFMPEG.

avcodec_send_packet() is returning error code -12.

I am trying to find what the meaning of -12 is.

I found this page but I can't understand the calculation for -12:

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

Can anyone help me?

I'm using DXVA2 for decoding. and avcodec_send_packet() function is return -12 after the 20th frame.

20th frame return

image

21st frame return

image

Solution

  • If you read the avcodec_send_packet() documentation, it says:

    Returns

    0 on success, otherwise negative error code: AVERROR(EAGAIN): input is not accepted in the current state - user must read output with avcodec_receive_frame() (once all output is read, the packet should be resent, and the call will not fail with EAGAIN). AVERROR_EOF: the decoder has been flushed, and no new packets can be sent to it (also returned if more than 1 flush packet is sent) AVERROR(EINVAL): codec not opened, it is an encoder, or requires flush AVERROR(ENOMEM): failed to add packet to internal queue, or similar other errors: legitimate decoding errors

    Note that avcodec_send_packet() is returning error codes based on the AVERROR() macro, which is defined in libavutil/error.h as:

    /* error handling */
#if EDOM > 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

    As you can see in the documentation, standard POSIX error codes are being passed to AVERROR().

    Now, if you go look at the POSIX error codes defined in your compiler's errno.h header, you'll find that [-]12 is defined as ENOMEM, which is one of the possible values mentioned in the avcodec_send_packet() documentation:

    AVERROR(ENOMEM): failed to add packet to internal queue, or similar other errors: legitimate decoding errors

    Which, according to this version of error.h (as opposed to this version) says:

    #if LIBAVUTIL_VERSION_MAJOR < 51
#define AVERROR_INVALIDDATA AVERROR(EINVAL)  
...
#define AVERROR_NOMEM       AVERROR(ENOMEM)  
...
#endif

    The screenshots you have shown are testing the return value of avcodec_send_packet() for AVERROR_INVALIDDATA instead of AVERROR_NOMEM.