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author | wm4 <wm4@nowhere> | 2019-11-06 21:36:02 +0100 |
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committer | wm4 <wm4@nowhere> | 2019-11-06 21:36:02 +0100 |
commit | f37f4de8496556afaa024e39e2efb433eb1680d4 (patch) | |
tree | 1ade8205598a3142d1fcbe5f32f461266ce81b76 /demux/demux_mkv.c | |
parent | abb089431d0467c3609207d0b27359ef08a6c16d (diff) | |
download | mpv-f37f4de8496556afaa024e39e2efb433eb1680d4.tar.bz2 mpv-f37f4de8496556afaa024e39e2efb433eb1680d4.tar.xz |
stream: turn into a ring buffer, make size configurable
In some corner cases (see #6802), it can be beneficial to use a larger
stream buffer size. Use this as argument to rewrite everything for no
reason.
Turn stream.c itself into a ring buffer, with configurable size. The
latter would have been easily achievable with minimal changes, and the
ring buffer is the hard part. There is no reason to have a ring buffer
at all, except possibly if ffmpeg don't fix their awful mp4 demuxer, and
some subtle issues with demux_mkv.c wanting to seek back by small
offsets (the latter was handled with small stream_peek() calls, which
are unneeded now).
In addition, this turns small forward seeks into reads (where data is
simply skipped). Before this commit, only stream_skip() did this (which
also mean that stream_skip() simply calls stream_seek() now).
Replace all stream_peek() calls with something else (usually
stream_read_peek()). The function was a problem, because it returned a
pointer to the internal buffer, which is now a ring buffer with
wrapping. The new function just copies the data into a buffer, and in
some cases requires callers to dynamically allocate memory. (The most
common case, demux_lavf.c, required a separate buffer allocation anyway
due to FFmpeg "idiosyncrasies".) This is the bulk of the demuxer_*
changes.
I'm not happy with this. There still isn't a good reason why there
should be a ring buffer, that is complex, and most of the time just
wastes half of the available memory. Maybe another rewrite soon.
It also contains bugs; you're an alpha tester now.
Diffstat (limited to 'demux/demux_mkv.c')
-rw-r--r-- | demux/demux_mkv.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c index 5eaa7bbb07..db1ccff13a 100644 --- a/demux/demux_mkv.c +++ b/demux/demux_mkv.c @@ -1999,13 +1999,9 @@ static int demux_mkv_open(demuxer_t *demuxer, enum demux_check check) if (demuxer->params) mkv_d->probably_webm_dash_init = demuxer->params->init_fragment.len > 0; - bstr start = stream_peek(s, 4); - uint32_t start_id = 0; - for (int n = 0; n < start.len; n++) - start_id = (start_id << 8) | start.start[n]; - if (start_id != EBML_ID_EBML) + // Make sure you can seek back after read_ebml_header() if no EBML ID. + if (stream_read_peek(s, &(char[4]){0}, 4) != 4) return -1; - if (!read_ebml_header(demuxer)) return -1; MP_DBG(demuxer, "Found the head...\n"); @@ -2027,7 +2023,6 @@ static int demux_mkv_open(demuxer_t *demuxer, enum demux_check check) while (1) { start_pos = stream_tell(s); - stream_peek(s, 4); // make sure we can always seek back uint32_t id = ebml_read_id(s); if (s->eof) { if (!mkv_d->probably_webm_dash_init) @@ -2836,7 +2831,6 @@ static int read_next_block_into_queue(demuxer_t *demuxer) find_next_cluster: mkv_d->cluster_end = 0; for (;;) { - stream_peek(s, 4); // guarantee we can undo ebml_read_id() below mkv_d->cluster_start = stream_tell(s); uint32_t id = ebml_read_id(s); if (id == MATROSKA_ID_CLUSTER) |