Embedded subtitles on mkvmerge-muxed files with compressed subtitle tracks
(the anime-release convention, reported against AV1 encodes) never rendered:
the track selected fine but nothing ever appeared on screen.
Two defects compounded. ContentCompAlgo 0 (zlib) is the Matroska default
value, so mkvmerge omits the element and the explicit-value detection never
engaged - media3 ignores an empty ContentCompression and silently emits
compressed samples. And for text subtitle tracks TrackOutput-level inflation
can never work: MatroskaExtractor prepends the plaintext timecode prefix to
the still-compressed payload and truncates the sample at the first NUL byte
before any TrackOutput runs, while AssTrackOutput feeds that same internal
buffer to libass, which then parses zero events and reports every frame as a
changed empty render.
Treat the presence of ContentCompression as zlib until an explicit
ContentCompAlgo says otherwise, and for SRT/ASS/SSA/VTT tracks inflate the
block frame payload before the parent's subtitle sample assembly, leaving the
TrackOutput wrapper to the formats it can actually handle. Blocks that are
laced, corrupt, or over-bound pass through byte-identical. The detection fix
also makes the existing whole-sample TrackOutput inflation engage for
PGS/VobSub zlib tracks, which media3 does not truncate.
Verified with mkvmerge zlib/plain fixture extraction tests and end-to-end on
an API 36 emulator against a Jellyfin direct-play mux mirroring the reported
file.
close#2023close#2022
Fire TV Stick 4K Max (and other Fire OS devices) advertise ENCODING_DTS_HD on
the HDMI route but only implement the DTS-HD basic profile, so media3's raw
path builds an AudioTrack that drains normally while the receiver hears
silence. The same routes do bitstream the 192kHz/7.1 ENCODING_IEC61937 carrier
TrueHD already rides, so DTS-HD MA access units are now packed into DTS type IV
bursts (a port of FFmpeg's spdif_header_dts4 at the 768kHz HD rate, the same
bytes Kodi's IEC packer produces) and played through that carrier.
The TrueHD MAT carrier sink is generalized into IecCarrierSink with one
IecCarrierPacker per codec. While the carrier route exists DTS-HD is binary -
the carrier or decoded PCM, never the lying raw path; routes without the
carrier keep the pre-carrier raw behavior. Master Audio peaks the carrier
cannot hold strip to the always-fitting core substream for ~60s, exactly as
FFmpeg does, and the packer output is pinned byte-for-byte against FFmpeg
spdif golden fixtures.
close#1988
MKV files whose Tracks element follows media clusters could direct-play with audio but no video. Upgrade Media3 to 1.11.0 and cover the extractor regression.
close#1947
Selection reads Format.sampleRate, but the rate family is only certain once a
major sync is parsed. When a container announces the 48kHz family and the
bitstream announces 44.1kHz, the packer emits nothing: handleBuffer consumed the
input and reported success, so the stream played as silence for as long as it
lasted. TrueHdMatPacker.reset also left the flag latched, so every later stream
on that packer emitted nothing too.
Leave the offending access unit in the buffer, signal the capability change, and
let the decoder take the stream over. The packer clears the flag on reset.
The latch has to outlive both flush and reset. media3 resets every renderer
disabled by a new selection before enabling its replacement
(ExoPlayerImplInternal.enableRenderers), and both audio renderers share this
sink, so the outgoing renderer's reset arrives in the middle of the handover the
latch exists to cause; clearing it there loops straight back into the mismatch.
The real boundary is a new media item, which only ExoPlayerCore knows, so it
signals one before setting a new source. The same-item recovery, DV-mode and
subtitle reloads deliberately do not.
It is a generation rather than a flag because that hook runs on the app thread
while the mismatch is found on the playback thread: a late buffer from the
outgoing stream would otherwise disable the carrier for its successor.
Verified on the SEI Box R (Android 14, armv7) with a genuine 44.1kHz TrueHD
stream in a container patched to announce 48000, so the bitstream and its
checksums stay valid. The sink enters the carrier at 192kHz, reports the
mismatch, hands over to FFmpeg and plays on. The device test asserts that
sequence from the sink's own diagnostics, because the mismatch fires before the
carrier opens an AudioTrack and the rate sequence alone cannot distinguish it
from never having selected the carrier.
Groundwork for bitstreaming TrueHD the way other players do (#1804).
Android will not bitstream raw TrueHD on the TV routes measured so far. Both
connected Android TV boxes report ENCODING_DOLBY_TRUEHD as offload-only while
reporting ENCODING_IEC61937 at 192kHz/7.1 as bitstream-capable, and the
reporter's box takes a raw TrueHD AudioTrack and then never advances its
playback head. Kodi models this split explicitly: it offers an "AudioTrack
(IEC)" sink where it packs the carrier itself and treats handing raw TrueHD to
Android as the fallback, and even that fallback runs at 192kHz. Media3 only
ever does the raw form, at the stream rate.
This adds the packer half: split a sample into TrueHD access units, assemble
MAT frames with timing-derived padding, and emit IEC 61937 bursts. It is a port
of FFmpeg's spdif_header_truehd rather than Kodi's CAEBitstreamPacker, because
Kodi's is a thin wrapper over an already-assembled buffer while the MAT code
placement and padding live in FFmpeg's stateful packer.
Details the port has to get right. Media3's Matroska path concatenates 16
syncframes into one sample, so access units are split here; reading a single
input_timing for sixteen frames would desynchronise the carrier. Burst buffers
alternate and are reused rather than allocated, because a fresh 61,440 byte
array every 20ms is roughly 3MB/s of garbage on the low-power hardware this
runs on. A 44.1kHz-family stream rides a 176.4kHz carrier instead of 192kHz,
which changes the whole AudioTrack tuple, so it is reported as unsupported for
the caller to decode instead.
A wrong byte here is not subtle — the receiver drops sync or renders full-scale
noise — so the test compares against FFmpeg's own output byte for byte, using
its input and output as fixtures.
No caller yet; the sink that routes TrueHD through this follows.
edde746