Log Message:
ffmpeg4: updated to 4.1.2

version 4.1.2:
- avcodec/dfa: Check the chunk header is not truncated
- avcodec/clearvideo: Check remaining data in P frames
- avcodec/hevcdec: decode at most one slice reporting being the first in the picture
- avcodec/dvbsubdec: Check object position
- avcodec/cdgraphics: Use ff_set_dimensions()
- avformat/gdv: Check fps
- configure: use vpx_codec_vp8_dx/cx for libvpx-vp8 checking
- configure: add missing pthreads extralibs dependency for libvpx-vp9
- avcodec/mpeg4videodec: Check idx in mpeg4_decode_studio_block()
- avcodec/dxv: Correct integer overflow in get_opcodes()
- avcodec/scpr: Fix use of uninitialized variable
- avcodec/qpeg: Limit copy in qpeg_decode_intra() to the available bytes
- avcodec/aic: Check remaining bits in aic_decode_coeffs()
- avcodec/gdv: Check for truncated tags in decompress_5()
- avcodec/bethsoftvideo: Check block_type
- avcodec/jpeg2000dwt: Fix integer overflow in dwt_decode97_int()
- avcodec/error_resilience: Use a symmetric check for skipping MV estimation
- avcodec/mlpdec: Insuffient typo
- avcodec/zmbv: obtain frame later
- avcodec/jvdec: Check available input space before decode8x8()
- avcodec/h264_direct: Fix overflow in POC comparission
- avformat/webmdashenc: Check id in adaption_sets
- avformat/http: Fix Out-of-Bounds access in process_line()
- avformat/ftp: Fix Out-of-Bounds Access and Information Leak in ftp.c:393
- avcodec/htmlsubtitles: Fixes denial of service due to use of sscanf in inner \ 
loop for handling braces
- avcodec/htmlsubtitles: Fixes denial of service due to use of sscanf in inner \ 
loop for tag scaning
- avformat/matroskadec: Do not leak queued packets on sync errors
- avcodec/mpeg4videodec: Clear interlaced_dct for studio profile
- avformat/mov: Do not use reference stream in mov_read_sidx() if there is no \ 
reference stream
- avcodec/sbrdsp_fixed.c: remove input value limit for sbr_sum_square_c()
- avcodec/prores_ks: Fix luma quantization if q >= MAX_STORED_Q
- avformat/mov: fix hang while seek on a kind of fragmented mp4
- avformat/async: fix assertion condition when draining buffer
- avcodec/cbs_av1: don't call cbs_av1_read_trailing_bits() when no bits remain \ 
in the OBU