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  1. 08 Oct, 2019 34 commits
  3. 07 Oct, 2019 6 commits
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Cosmetics · 1d54309c
      Andreas Rheinhardt authored 
      Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      1d54309c
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Don't leave stale pointer in memory · 5873feac
      Andreas Rheinhardt authored 
      Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      5873feac
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Don't modify size of the input buffer · 87b30f8a
      Andreas Rheinhardt authored 
      When flushing, MAX_FRAME_HEADER_SIZE bytes (always zero) are supposed to
be written to the fifo buffer in order to be able to check the rest of
the buffer for frame headers. It was intended to write these by writing
a small buffer of size MAX_FRAME_HEADER_SIZE to the buffer. But the way
it was actually done ensured that this did not happen:

First, it would be checked whether the size of the input buffer was zero,
in which case it buf_size would be set to MAX_FRAME_HEADER_SIZE and
read_end would be set to indicate that MAX_FRAME_HEADER_SIZE bytes need
to be written. Then it would be made sure that there is enough space in
the fifo for the data to be written. Afterwards the data is written. The
check used here is for whether buf_size is zero or not. But if it was
zero initially, it is MAX_FRAME_HEADER_SIZE now, so that not the
designated buffer for writing MAX_FRAME_HEADER_SIZE is written; instead
the padded buffer (from the stack of av_parser_parse2()) is used. This
works because AV_INPUT_BUFFER_PADDING_SIZE >= MAX_FRAME_HEADER_SIZE.
Lateron, buf_size is set to zero again.

Given that since 7edbd536, the actual amount of data read is no longer
automatically equal to buf_size, it is completely unnecessary to modify
buf_size at all. Moreover, modifying it is dangerous: Some allocations
can fail and because buf_size is never reset to zero in this codepath,
the parser might return a value > 0 on flushing.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      87b30f8a
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Remove superfluous checks · a1701e75
      Andreas Rheinhardt authored 
      For a parser, the input buffer is always != NULL: In case of flushing,
the indicated size of the input buffer will be zero and the input buffer
will point to a zeroed buffer of size 0 + AV_INPUT_BUFFER_PADDING.
Therefore one does not need to check for whether said buffer is NULL or
not.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      a1701e75
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Fix number of buffered headers · 047a6d39
      Andreas Rheinhardt authored 
      Only decrement the number of buffered headers if a header has actually
been freed.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      047a6d39
    • Andreas Rheinhardt's avatar
      avcodec/flac_parser: Fix off-by-one error · e5e5be4c
      Andreas Rheinhardt authored 
      The flac parser uses a fifo to buffer its data. Consequently, when
searching for sync codes of flac packets, one needs to take care of
the possibility of wraparound. This is done by using an optimized start
code search that works on each of the continuous buffers separately and
by explicitly checking whether the last pre-wrap byte and the first
post-wrap byte constitute a valid sync code.

Moreover, the last MAX_FRAME_HEADER_SIZE - 1 bytes ought not to be searched
for (the start of) a sync code because a header that might be found in this
region might not be completely available. These bytes ought to be searched
lateron when more data is available or when flushing.

Unfortunately there was an off-by-one error in the calculation of the
length to search of the post-wrap buffer: It was too large, because the
calculation was based on the amount of bytes available in the fifo from
the last pre-wrap byte onwards. This meant that a header might be
parsed twice (once prematurely and once regularly when more data is
available); it could also mean that an invalid header will be treated as
valid (namely if the length of said invalid header is
MAX_FRAME_HEADER_SIZE and the invalid byte that will be treated as the
last byte of this potential header happens to be the right CRC-8).

Should a header be parsed twice, the second instance will be the best child
of the first instance; the first instance's score will be
FLAC_HEADER_BASE_SCORE - FLAC_HEADER_CHANGED_PENALTY ( = 3) higher than
the second instance's score. So the frame belonging to the first
instance will be output and it will be done as a zero length frame (the
difference of the header's offset and the child's offset). This has
serious consequences when flushing, as returning a zero length buffer
signals to the caller that no more data will be output; consequently the
last frames not yet output will be dropped.

Furthermore, a "sample/frame number mismatch in adjacent frames" warning
got output when returning the zero-length frame belonging to the first
header, because the child's sample/frame number of course didn't match
the expected sample frame/number given its parent.

filter/hdcd-mix.flac from the FATE-suite was affected by this (the last
frame was omitted) which is the reason why several FATE-tests needed to
be updated.

Fixes ticket #5937.
Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
      e5e5be4c