This will result in poor quality audio for SSR streams, but they
will at least demux and decode without error; partially fixing
ticket #1693.
This just pulls in the decode_gain_control() function from the
ffmpeg summer-of-code repo (original author Robert Swain) at
svn://svn.mplayerhq.hu/soc/aac/aac.c and adds AOT_AAC_SSR to
decode_audio_specific_config_gb().
Signed-off-by: Dale Curtis <dalecur...@chromium.org>
Co-authored-by: Robert Swain <robert.sw...@gmail.com>
From 97380752ef12337d9b9a01801a9a84df3b4b9c0a Mon Sep 17 00:00:00 2001
From: Dale Curtis <dalecur...@chromium.org>
Date: Thu, 15 Feb 2018 16:22:55 -0800
Subject: [PATCH] [aacdec] Parse and drop gain control data, so that SSR
packets decode.
This will result in poor quality audio for SSR streams, but they
will at least demux and decode without error; partially fixing
ticket #1693.
This just pulls in the decode_gain_control() function from the
ffmpeg summer-of-code repo (original author Robert Swain) at
svn://svn.mplayerhq.hu/soc/aac/aac.c and adds AOT_AAC_SSR to
decode_audio_specific_config_gb().
Signed-off-by: Dale Curtis <dalecur...@chromium.org>
Co-authored-by: Robert Swain <robert.sw...@gmail.com>
---
libavcodec/aacdec_template.c | 49 +++++++++++++++++++++++++++++++++---
1 file changed, 46 insertions(+), 3 deletions(-)
diff --git a/libavcodec/aacdec_template.c b/libavcodec/aacdec_template.c
index c2d9802023..c3ec3eefe8 100644
--- a/libavcodec/aacdec_template.c
+++ b/libavcodec/aacdec_template.c
@@ -997,6 +997,7 @@ static int decode_audio_specific_config_gb(AACContext *ac,
switch (m4ac->object_type) {
case AOT_AAC_MAIN:
case AOT_AAC_LC:
+ case AOT_AAC_SSR:
case AOT_AAC_LTP:
case AOT_ER_AAC_LC:
case AOT_ER_AAC_LD:
@@ -1967,6 +1968,44 @@ static void apply_prediction(AACContext *ac, SingleChannelElement *sce)
reset_all_predictors(sce->predictor_state);
}
+static int decode_gain_control(SingleChannelElement * sce, GetBitContext * gb)
+{
+ // wd_num, wd_test, aloc_size
+ static const int gain_mode[4][3] = {
+ {1, 0, 5}, // ONLY_LONG_SEQUENCE = 0,
+ {2, 1, 2}, // LONG_START_SEQUENCE,
+ {8, 0, 2}, // EIGHT_SHORT_SEQUENCE,
+ {2, 1, 5}, // LONG_STOP_SEQUENCE
+ };
+
+ // per-element gain control for SSR
+ struct {
+ int max_band;
+ int adjust_num[4][8];
+ int alev[4][8][8];
+ int aloc[4][8][8];
+ } ssr;
+
+ const int mode = sce->ics.window_sequence[0];
+ int bd, wd, ad;
+
+ // FIXME: Store the gain control data on |sce| and do something with it.
+ ssr.max_band = get_bits(gb, 2);
+ for (bd = 0; bd < ssr.max_band; bd++) {
+ for (wd = 0; wd < gain_mode[mode][0]; wd++) {
+ ssr.adjust_num[bd][wd] = get_bits(gb, 3);
+ for (ad = 0; ad < ssr.adjust_num[bd][wd]; ad++) {
+ ssr.alev[bd][wd][ad] = get_bits(gb, 4);
+ if (wd == 0 && gain_mode[mode][1])
+ ssr.aloc[bd][wd][ad] = get_bits(gb, 4);
+ else
+ ssr.aloc[bd][wd][ad] = get_bits(gb, gain_mode[mode][2]);
+ }
+ }
+ }
+ return 0;
+}
+
/**
* Decode an individual_channel_stream payload; reference: table 4.44.
*
@@ -2034,9 +2073,13 @@ static int decode_ics(AACContext *ac, SingleChannelElement *sce,
goto fail;
}
if (!eld_syntax && get_bits1(gb)) {
- avpriv_request_sample(ac->avctx, "SSR");
- ret = AVERROR_PATCHWELCOME;
- goto fail;
+ // FIXME: Do something with the gain control data...
+ ret = decode_gain_control(sce, gb);
+ if (ret < 0) {
+ ret = AVERROR_PATCHWELCOME;
+ avpriv_request_sample(ac->avctx, "SSR");
+ goto fail;
+ }
}
// I see no textual basis in the spec for this occurring after SSR gain
// control, but this is what both reference and real implmentations do
--
2.16.1.291.g4437f3f132-goog
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
