This reverts commit b7f90be567.
The author agreed to the relicensing now (if that code is affected by
the original copyright at all - that was the only line possibly left of
it).
If tags like TITLE have the whole parameter in " quotes, strip them.
Also remove the leading whitespace, since even with a single space it
was always included.
Fixes#5462.
Move dec_video.c to filters/f_decoder_wrapper.c. It essentially becomes
a source filter. vd.h mostly disappears, because mp_filter takes care of
the dataflow, but its remains are in struct mp_decoder_fns.
One goal is to simplify dataflow by letting the filter framework handle
it (or more accurately, using its conventions). One result is that the
decode calls disappear from video.c, because we simply connect the
decoder wrapper and the filter chain with mp_pin_connect().
Another goal is to eventually remove the code duplication between the
audio and video paths for this. This commit prepares for this by trying
to make f_decoder_wrapper.c extensible, so it can be used for audio as
well later.
Decoder framedropping changes a bit. It doesn't seem to be worse than
before, and it's an obscure feature, so I'm content with its new state.
Some special code that was apparently meant to avoid dropping too many
frames in a row is removed, though.
I'm not sure how the source code tree should be organized. For one,
video/decode/vd_lavc.c is the only file in its directory, which is a bit
annoying.
This is supposed to help making data flow easier and wakeup handling
more efficient. Once that change is done, reading a packet on any
stream won't have to wakeup and poll all decoders (which helps reducing
the mess even if all decoders are on the same thread).
This also improves the accuracy of wakeups by tracking better whether
a wakeup is needed.
AV_DISPOSITION_ATTACHED_PIC usually means the video track isn't real,
and merely reflects the presence of an embedded image in tag data (such
as ID3v2 tags), with some inconsistent hack to make libavformat return
it as video packet once.
Except it doesn't mean that. It can be randomly set on other streams
that do sort of behave like video streams, such as chapter thumbnail
tracks in mp4 files. AV_DISPOSITION_TIMED_THUMBNAILS is set in these
cases. In theory, there can supposedly be more such cases, but only the
chapter thumbnail one currently exists. So add it as exception.
This restores displaying these thumbnails as video frames, for better or
worse. (Before, only the first thumbnail was displayed.)
Requires newest FFmpeg git, which has a change that makes the HLS
demuxer set an AVFMTCTX_UNSEEKABLE flag if seeking is not available,
which is the case for HLS live streams. This should make the player
frontend behave pretty well, instead of crapping up irrecoverably.
And use it for 2 demuxer options. It could be used for more options
later. (Though the --cache options can not use this, because they use KB
as base unit.)
I found that at least for mjpeg streams, FFmpeg will set packet pts/dts
anyway. The mjpeg raw video demuxer (along with some other raw formats)
has a "framerate" demuxer option which defaults to 25, so all mjpeg
streams will be played at 25 FPS by default.
mpv doesn't like this much. If AVFMT_NOTIMESTAMPS is set, it prints a
warning, that might print a bogus FPS value for the assumed framerate.
The code was originally written with the assumption that FFmpeg would
not set pts/dts for such formats, but since it does, the printed
estimated framerate will never be used. --fps will also not be used by
default in this situation.
To make this hopefully less confusing, explicitly state the situation
when the AVFMT_NOTIMESTAMPS flag is set, and give instructions how to
work it around.
Also, remove the warning in dec_video.c. We don't know what FPS it's
going to assume anyway. If there are really no timestamps in the stream,
it will trigger our normal missing pts workaround. Add the assumed FPS
there.
In theory, we could just clear packet timestamps if AVFMT_NOTIMESTAMPS
is set, and make up our own timestamps. That is non-trivial for advanced
video codecs like h264, so I'm not going there. For seeking and
buffering estimation the situation thus remains half-broken.
This is a mitigation for #5419.
It was actually already implemented as ta_dup_ptrtype(), but that seems
like a clunky name. Also we still use the talloc_ names throughout the
source, and I'd rather use an old name instead of a mixing inconsistent
naming conventions.
If you play a video with an external audio track, and do backwards
keyframe seeks, then audio can be missing. This is because a backwards
seek can end up way before the seek target (this is just how this seek
mode works). The audio file will be seeked at the correct seek target
(since audio usually has a much higher seek granularity), which results
in silence being played until the video reaches the originally intended
seek target.
There was a hack in audio.c to deal with this. Replace it with a
different hack. The new hack probably works about as well as the old
hack, except it doesn't add weird crap to the audio resync path (which
is some of the worst code here, so this is some nice preparation for
rewriting it). As a more practical advantage, it doesn't discard the
audio demuxer packet cache. The old code did, which probably ruined
seeking in youtube DASH streams.
A non-hacky solution would be handling external files in the demuxer
layer. Then chaining the seeks would be pretty easy. But we're pretty
far from that, because it would either require intrusive changes to the
demuxer layer, or wouldn't be flexible enough to load/unload external
files at runtime. Maybe later.
Similar to 1eec7d2315, but for the beginning of the stream (named BOF in
this commit).
We can know this only if demuxing actually started from the beginning.
If there is a seek to the beginning (even if you use --start=-1000), we
don't know in general whether the demuxer truly returns the start of the
file. We could probably make a heuristic with assuming that this is what
happens if the seek target is before the start time or so, but this is
not included in this commit.
libavformat's cover art hack (aka attached pictures) breaks the ability
of the demuxer cache to keep multiple seek ranges. This happens because
the cover art packet has neither position nor timestamp, and libavformat
gives us the packet even though we intended to drop it.
The cover art hack works by adding the cover art packet to the read
packet stream once when demuxing starts (or after seeks). mpv treats
cover art in a similar way internally, but we have to compensate for
libavformat's shortcomings, and add the cover art packet ourselves when
we need it. So we don't want libavformat to return the packet.
We normally prevent this in demux_lavc.c/select_tracks() and explicitly
disable cover art streams. (We add it in dequeue_packet() instead.) But
libavformat will actually add the cover art packet even if we disable
the cover art stream, because it adds it at initialization time, and
does not bother to check again in av_read_frame() (apparently). The
packet is actually read, and upsets the demuxer cache logic. In
addition, this also means we probably decoded the cover art picture
twice in some situations.
Fix this by explicitly checking/discarding this in yet another place.
(Screw this hack...)
The impact was that you couldn't exactly seek to the join point with a
keyframe seek, even though there was a keyframe. This commit fixes it by
preserving the necessary metadata that got lost on cached range joining.
This is so absurdly obscure that it gets a longer code comment.
This warning was printed when the demuxer cache tried to join two
adjacent seek ranges, but failed if the last keyframe in the second
range was within the (overlapping) first range. This is a weird corner
case which to support probably would not be worth it.
So this code just printed a warning and discarded the second range. As
it turns out, this can happen relatively often if you seek a lot, and
the seek ranges are very tiny (such as consisting of only 1 keyframe).
Dropping the second range in these cases is OK and probably cheaper than
trying to actually join them. Change the warning to verbose level.
(It seems this could actually be "supported", because if keyframe_latest
is not set, there will be no other keyframes, so it could just be unset,
with the exception that q1->keyframe_latest in the code below must not
be overwritten. But still, too much trouble for a special case that
likely does not matter, and it would have to be tested too.)
This means if the user tries to seek past EOF, and we know EOF was seen
already, then use a cached seek, instead of triggering a low level seek.
This requires some annoying tracking, but seems pretty simple otherwise.
One advantage of doing this is that if the user tries to do this kind of
seek, there's no unnecessary waiting for a reaction by network (and in
most cases, redundant downloading of data just to discard it again).
Another is that this avoids creating overlapping seek ranges: previously, the
low level seek would naturally create a new range. Then it would read and add
data from the end of the stream due to the low level demuxer not being able to
seek to the target and selecting the last seek point before the end of the
stream. Consequently, this new range would overlap with the previous cached
range. But since the cache joining code is written such that you join the
current range with the _next_ range (instead of the previous as it would be
needed in this case), the overlapping ranges were left alone, until seeking back
to the previous range. That was ugly, sort of harmless, and could happen in
other cases, but this avoidable case was pretty easy to trigger.
Export them as explicitly undocumented debugging fields for the
"demuxer-cache-state" property.
Should be somewhat helpful to debug "wtf is the demuxer" doing
situations better, especially when seeking. It also becomes visible how
long the demuxer is blocked on an "old" seek when you keep seeking while
the first seek hasn't finished.
update_seek_ranges() has some special code that attempts to correctly
adjust seek ranges for subtitle tracks. (Subtitle are a nightmare for
seek ranges, because they are sparse, so using the packet list is not
enough to reliably determine the valid cached range.)
This had code like this inside the modified if statement:
range->seek_start = MP_PTS_MAX(range->seek_start, <something>);
If seek_start is NOPTS, then seek_start will be set to <something>,
breaking some other code that checks seek_start for NOPTS to see if it's
empty. Fix this by explicitly checking whether seek_start is NOPTS
before adjusting it.
The crash happened in prune_old_packets() because the range was marked
as non-empty, yet there was no packet in it to prune. This was with
files with muxed subtitles, when seeking back to the start. This should
not happen anymore with the change. Also add an assert() to
check_queue_consistency() that checks for this specific case.
There's still some mess. In theory, subtitle tracks could be completely
empty, yet their seek range would span the entire file. Seek range
tracking of subtitle files is slightly broken (even before this change).
Some of this should probably be revisited later, including not just
using seek_start to determine whether a seek range should be pruned due
to being empty.
The x264 hack requires reading the first video packet, which in turn we
handle with a hack in demux_mkv.c to get the packet without having to
add special crap to demux.c. Another useless MKV feature (which they
enabled by default at one point and which caused many demuxers to break
completely, only to disable it again when it was too late) conflicts
with this, because we actually pass a block as packet contents, instead
of after "decompression".
Fix this by calling demux_mkv_decode().
This fixes when resuming certain broken h264 files encoded by x264. See
FFmpeg commit 840b41b2a643fc8f0617c0370125a19c02c6b586 about the x264
bug itself.
Normally, the unregistered user data SEI (that contains the x264 version
string) is informational only. But libavcodec uses it to workaround a
x264 bug, which was recently fixed in both libavcodec and x264. The fact
that both encoder and decoder were buggy is the reason that it was not
found earlier, and there are apparently a lot of files around created by
the broken decoder. If libavcodec sees the SEI, this bug can be worked
around by using the old behavior.
If you resume a file with mpv (i.e. seeking when the file loads),
libavcodec never sees the first video packet. Consequently it has to
assume the file is not broken, and never applies the workaround,
resulting in garbage being played.
Fix this by always feeding the first video packet to the decoder on
init, and then flushing the codec (to avoid that an unwanted image is
output). Flushing the codec does not remove info such as the x264
version. We also abuse the fact that the first avcodec_send_packet()
always pushes the frame into the decoder (so we don't have to trigger
the decoder by requsting an output frame).
This will help with things like livestreams.
As a minor detail, subtitles are excluded, because they sometimes have
"unused" events after video and audio ends. To avoid this annoying
corner case, just ignore them.
Before this change and before the seekable stream cache became a thing,
we could possibly seek using the stream cache. But we couldn't know
whether the seek would succeed. We knew the available byte range, but
could in general not tell whether a demuxer would stay within the range
when trying to seek to a specific time position. We preferred to have
safe defaults, so seeking in streams that were detected as unseekable
were not honored. We allowed overriding this via --force-seekable=yes,
in which case it depended on your luck whether the seek would work, or
the player crapped its pants.
With the demuxer packet cache, we can tell exactly whether a seek will
work (at least if there's only 1 seek range). We can just let seeks go
through. Everything to allow this is already in place, and this commit
just moves around some minor things.
Note that the demux_seek() return value was not used before, because low
level (i.e. network level) seeks are usually asynchronous, and if they
fail, the state is pretty much undefined. We simply repurpose the return
value to signal whether cache seeking worked. If it didn't, we can just
resume playback normally, because demuxing continues unaffected, and no
decoder are reset.
This should be particularly helpful to people who for some reason stream
data into stdin via streamlink and such.
Caused by the relatively recent change to packet parsing. This time it
was probably triggered by lace type 0, which reduces the byte length of
a 0 sized packet to 3 (timestamp + flag) instead of 4 (lace count for
other lace types). The thing about laces is just my guess why it worked
for other 0 sized packets, though.
Also remove the redundant and now incorrect check below.
Fixes#5271.
This log line tells us why the demuxer is trying to read more, which us
useful when debugging queue overflows. Probably barely useful, but I
think keeping that flag separately also makes the code slightly easier
to understand.
This fixes weird behavior in the following case:
- open a file
- make sure the max. demuxer forward cache is smaller than the
file's video track
- make sure the max. readahead duration is larger than the file's
duration
- disable the audio track
- seek to the beginning of the file
- once the cache has filled enable the audio track
- a queue overflow warning should appear
(- looking at the seek ranges is also interesting)
The queue overflow warning happens because the packed queue for the
video track will use up the full quota set by --demuxer-max-bytes. When
the audio track is enabled, reading an audio packet would technically
overflow the packet cache by the size of whatever packet is read next.
This means the demuxer signals EOF to the decoder, and once playback has
consumed enough video packets so that audio packets can be read again,
the decoder resumes from EOF. This interacts badly with A/V
synchronization and the whole thing can randomly crap itself until audio
has fully recovered.
We didn't care about this so far, but we want to raise the readahead
duration to something very high, so that the demuxer cache is fully
used. This means this case can be hit quite quickly by switching audio
or subtitle tracks, and is not really an obscure corner case anymore.
Fix this by always losing all cache. Since the cache can't be used
anyway until the newly selected track has been read, this is not much of
a disadvantage. The only thing that could be brought up is that
unselecting the track again could resume operation normally. (Maybe this
would be useful if network died completely without chance of recovery.
Then you could watch the already buffered video anyway by deselecting
the audio track again.) But given the headaches, this seems like the
better solution.
Unfortunately this requires adding new new strange fields and strangely
fragmenting state management functions again. I'm sure whoever works on
this in the future will hate me. Currently it seems like the lesser
evil, and much simpler and robust than the other potential solutions.
In case this needs to be revisited, here is a reminder for readers from
the future what alternative solutions were considered, without those
disadvantages:
A first attempted solution allowed the demuxer to buffer some additional
packets on track switching. This would allow it to read enough data to
feed the decoder at least. But it was still awkward, as it didn't allow
the demuxer to continue prefetching the newly selected track. It also
barely worked, because you could make the forward buffer "over full" by
seeking back with seekable cache enabled, and then it couldn't read
packets anyway.
As alternative solution, we could always demux and cache all tracks,
even if they're deselected. This would also not require a network-level
seek for the "refresh" logic (it's the thing that lets the video decoder
continue as if nothing happened, while actually seeking back in the
stream to get the missing audio packets, in the case of enabling a
previously disabled audio track). But it would also possibly waste
network and memory resources, depending on what the user actually wants.
A second solution would just account the queue sizes for each stream
separately. We could freely fill up the audio packet queue, even if the
video queue is full. Since the demuxer API returns interleaved packets
and doesn't let you predict which packet type comes next, this is not as
simple as it sounds, but it'd probably tie in nicely with the "refresh"
logic.
A third solution would be removing buffered video packets from the end
of the packet queue. Since the "refresh" logic gets these anyway, there
is no reason to keep them if they prevent the audio packet queue from
catching up with the video one. But this would require additional logic,
would interact badly with a bunch of other corner cases. And as far as
the code goes, it's rather complex, because all the logic is written
with FIFO behavior in mind (including the fact that the packet queue is
a singly linked list with no backwards links, making removal from the
end harder).
It seems like there's nothing stopping from sub-demuxers from keeping
packets in the cache, even if it's completely pointless. The top-most
demuxer (demux_timeline) already takes care of caching, so sub-demuxers
only waste space and time with this.
Add a function that can disable the packet cache even at runtime and
after packets are read. (It's not clear whether it really can happen
that packets are read before demux_timeline gets the sub-demuxers, but
there's no reason to make it too fragile.) Call it on all sub-demuxers.
For this to work, it seems we have to move the code for setting the
seekable_cache flag to before demux_timeline is potentially initialized,
because otherwise the cache would be reenabled if the demuxer triggering
timeline support is a timeline segment itself (e.g. ordered chapters).
This fixes missing audio when cycling through audio tracks with anything
that uses nested demuxers, such as demux_timeline, which us used for
EDL, --merge-files, ordered chapters, and youtube-dl pseudo DASH
support. When this bug happened, reenabling an audio track would lead to
silence for the duration of the readahead amount.
The underlying reason is the incorrectly updated buffered range on track
switch. It accidentally included the amount covered by the deselected
stream. But the cause of the observed effect was that demux_timeline
issued a refresh seek to the underlying slave demuxer, which in turn
thought it could do a cache seek, because the seek range still included
everything.
update_stream_selection_state() calls update_seek_ranges() to update the
seek ranges after a track switch. When reenabling the track, ds->eager
was set to false during update_seek_ranges(), which made it think the
stream was sparse, and thus it didn't restrict the current seek range
(making later code think everything was buffered). Fix this by moving
some code, so we first update the ds->eager flag, then the seek ranges.
Also verbose log the low level stream selection calls.
Always display the duration as "unknown" if the duration is known. Also
fix that at least demux_lavf reported unknown duration as 0 (fix by
setting the default to unknown in demux.c).
Remove the dumb _u formatter function, and use a different approach to
avoiding displaying "unknown" as playback time on playback start (set
last_seek_pts for that).
This gives the filename or URL to the libavformat probing logic, which
might use the file extension as a "help" to decide which format the file
is. This helps with mp3 files that have large id3v2 tags and prevents
the idiotic ffmpeg probing logic to think that a mp3 file is amr.
(What we really want is knowing whether we _really_ need to feed more
data to libavformat to detect the format. And without having to pre-read
excessive amounts of data for relatively normal streams.)
If the backbuffer is much larger than the forward buffer, and if you
join a small range with a large range (larger than the forward buffer),
then the seek issues to the end of the range after joining will overflow
the queue.
Normally, read_more will be false when the forward buffer is full, but
the resume seek after joining will set need_refresh to true, which
forces more reading and thus triggers the overfloe warning.
Attempt to fix this by not setting read_more to true on refresh seeks.
Set prefetch_more instead. read_more will still be set if an A/V stream
has no data.
This doesn't help with the following problems related to using refresh
seeks for track switching:
- If the forward buffer is full, then enabling another track will
obviously immediately overflow the queue, and immediately lead to
marking the new track as having no more data (i.e. EOF). We could cut
down the forward buffer or so, but there's no simple way to implement
it. Another possibility would be dropping all buffers and trying to
resume again, but this would likely be complex as well.
- Subtitle tracks will not even show a warning (because they are sparse,
and we have no way of telling whether a packet is missing, or there's
just no packet near the current position). Before this commit,
enabling an empty subtitle track would probably have overflown the
queue, because ds->refreshing was never set to true. Possibly this
could be solved by determining a demuxer read position, which would
reflect until which PTS all subtitle packets should have been demuxed.
The forward buffer limit was intended as a last safeguard to avoid
excessive memory usage against badly interleaved files or decoders going
crazy (up to reading the whole into memory and OOM'ing the user's
system). It's not good at all to limit prefetch. Possibly solutions
include having another smaller limit for prefetch, or maybe having only
a total buffer limit, and discarding back buffer if more data has to be
read. The current solution is making the forward buffer larger than the
forward duration (--cache-secs) would require, but of course this
depends on the stream's bitrate.
The option for enabling it has now an "auto" choice, which is the
default, and which will enable it if the media is thought to be via
network or if the stream cache is enabled (same logic as --cache-secs).
Also bump the --cache-secs default from 10 to 120.
Some back buffer is required to make the immediate forward range
seekable. This is because the back buffer limit is strictly enforced.
Just set a rather high back buffer by default. It's not use if
--demuxer-seekable-cache is disabled, so this is without risk.
Limit the number of cached ranges to MAX_SEEK_RANGES, which is the same
number of maximally exported seek ranges. It makes no sense to keep
them, as the user won't see them anyway. Remove the smallest ones to
enforce the limit if the number grows too high.
Helps a little bit, I guess. But in general, t(h)rashing the cache kills
us anyway.
This has a fixed number of index entries. Entries are added/removed as
packets go through the packet queue. Only keyframes after index_distance
seconds are added. If there are too many keyframe packets, the existing
index is reduced by half, and index_distance is doubled. This should
provide somewhat even spacing between the entries.
The packet queue is sorted, so we can stop the search if we have found a
packet, and the next packet in the queue has a higher PTS than the seek
PTS (for the sake of SEEK_FORWARD, we still consider the first packet
with a higher PTS).
Also, as a mostly cosmetic change, but which might be "faster", check
target for NULL, instead of target_diff for a magic float value.
Subtitle streams are sparse, and no overlap is required to correctly
join two cached ranges. This was not correctly handled iff the two
ranges had different subtitle packets close to the join point.
demux_add_packet() must completely ignore any packets that are added
while a queued seek is not initiated yet.
The main issue is that after setting in->seeking==true, the central lock
is released, and it can take "a while" until it's reacquired on the
demux thread and the seek is actually initiated. During that time,
packets could be read and added, that have nothing to do with the new
state.
If subtitles are part of the stream, determining the seekable range
becomes harder. Subtitles are sparse, and can have packets in irregular
intervals, or even completely lack packets. The usual logic of computing
the seek range by the min/max packet timestamps fails.
Solve this by making the only assumption we can make: subtitle packets
are implicitly demuxed along with other packets. We also assume perfect
interleaving for this, but you really can't do anything with sparse
packets that makes sense without this assumption.
One special case is if we prune sparse packets within the current
seekable range. Obviously this should limit the seekable range to after
the pruned packet.
