The MPEG-PS muxer uses a custom queue of custom packets. To keep track
of it, it has a pointer (named predecode_packet) to the head of the
queue and a pointer to where the next packet is to be added (it points
to the next-pointer of the last element of the queue); furthermore,
there is also a pointer that points into the queue (called premux_packet).
The exact behaviour was as follows: If premux_packet was NULL when a
packet is received, it is taken to mean that the old queue is empty and
a new queue is started. premux_packet will point to the head of said
queue and the next_packet-pointer points to its next pointer. If
predecode_packet is NULL, it will also made to point to the newly
allocated element.
But if premux_packet is NULL and predecode_packet is not, then there
will be two queues with head elements premux_packet and
predecode_packet. Yet only elements reachable from predecode_packet are
ever freed, so the premux_packet queue leaks.
Worse yet, when the predecode_packet queue will be eventually exhausted,
predecode_packet will be made to point into the other queue and when
predecode_packet will be freed, the next pointer of the preceding
element of the queue will still point to the element just freed. This
element might very well be still reachable from premux_packet which
leads to use-after-frees lateron. This happened in the tickets mentioned
below.
Fix this by never creating two queues in the first place by checking for
predecode_packet to know whether the queue is empty. If premux_packet is
NULL, then it is set to the newly allocated element of the queue.
Fixes tickets #6887, #8188 and #8266.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit cfce16449cb815132f829d5a07beb138dfb2cba6)
Fixes: signed integer overflow: -9223372036854775808 - 45000 cannot be represented in type 'long'
Fixes: ticket8187
Found-by: Suhwan
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 9874815b1aadadd7fd19aa6aabb7d9193f2f43d5)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
The MPEG-PS muxer only accepts PCM streams having up to 8 channels
and the following sampling rates: 32/44.1/48/96 kHz.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
PCM_S16BE stream packets in MPEG-PS have a 3-byte header and
are recognized as PCM_DVD by the demuxer which prevents their
correct remuxing in MPEG-1/2 PS.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
* commit '8c6f430291374cf6d2cfb85cdbb809803b5a7d83':
mpeg: Suppress a compiler warning on callback type
Conflicts:
libavformat/mpegenc.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>
