FFmpeg Multiple Vulnerabilities

Multiple vulnerabilities have been identified in FFmpeg, which can be exploited by malicious people to compromise an application using the library.

1. A format string error exists within the "srt_to_ass()" function (libavcodec/srtdec.c) when parsing certain parameters.
2. An integer overflow error exists within the "dirac_unpack_block_motion_data()" function (libavcodec/diracdec.c) when handling certain motion data.
3. An integer overflow error exists within the "sws_init_context()" function (libswscale/utils.c) when decoding certain scale data.

Successful exploitation of the vulnerabilities may allow execution of arbitrary code.