tvOS 上的 FFMPEG 多播

Question

我正在尝试在 tvOS 上使用 FFMPEG 打开多播流，但使用以下命令:

avformat_open_input(&pFormatCtx, [sdpString UTF8String], NULL, NULL)

失败并显示错误代码 -1094995529 并打印错误

setsockopt(MCAST_JOIN_SOURCE_GROUP): Can't assign requested address

这是位于 udp.c 中的失败 FFMPEG 代码片段

    if (setsockopt(sockfd, level,
                   include ? MCAST_JOIN_SOURCE_GROUP : MCAST_BLOCK_SOURCE,
                   (const void *)&mreqs, sizeof(mreqs)) < 0) {
        if (include)
            log_net_error(NULL, AV_LOG_ERROR, "setsockopt(MCAST_JOIN_SOURCE_GROUP)");
        else
            log_net_error(NULL, AV_LOG_ERROR, "setsockopt(MCAST_BLOCK_SOURCE)");
        return ff_neterrno();
    }

Answer 1

您拥有的错误代码可以解码如下。来自 ffmpeg 的错误代码(来自 avutil 的 error.h):
http://ffmpeg.org/doxygen/trunk/error_8h_source.html

原来您指定的值是:

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

-1094995529 变为 -0x41444E49，当您查看这些字母时，在 ACSII 中，0x41 = 'A'、0x44 = 'D'、0x4E = 'N 和 0x49 = 'I'。由于宏/等事情是相反的，所以ADNI变成了INDA，你可以从#define片段中看到，是AVERROR_INVALIDDATA定义的FFERRTAG('I'，'N'，'D'，'A')。

其余的错误代码在该文件中，我已将它们粘贴在下面:

#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')