On 19.11.2015 01:31, Michael Niedermayer wrote:
> On Thu, Nov 19, 2015 at 12:31:17AM +0100, Andreas Cadhalpun wrote:
>> So far so good. However, the next time sbr_dequant is called this breaks:
>> noise_facs[1][0].exp = 6 - 536870912 + 1 = -536870905;
>>
>
>> This is obviously completely bogus.
>
> yes
>
>
>> Instead this code needs a function like av_exp2_sf.
>
> no, thats not the problem
> this code is missing error checks and only adding error checks will
> fix that
>
> there is read_sbr_noise() which reads data
> there is sbr_dequant() which converts the data from "read data" to
> lets call it "dequantized data"
That makes sense, thanks for explaining.
> what you describe sounds like that sbr_dequant() is called on top of
> the output from sbr_dequant(), that sounds like a error condition
> for both fixed and float
Indeed. A patch checking for that is attached.
Best regards,
Andreas
>From 0237ebfca9571d2d3e51f5c5dc15f8f5a516510a Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
Date: Fri, 20 Nov 2015 00:04:50 +0100
Subject: [PATCH] aacsbr: don't call sbr_dequant twice without intermediate
read_sbr_data
Doing that doesn't make sense, because the only purpose of sbr_dequant
is to process the data from read_sbr_data.
Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
libavcodec/aacsbr_template.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/libavcodec/aacsbr_template.c b/libavcodec/aacsbr_template.c
index cf18862..564930a 100644
--- a/libavcodec/aacsbr_template.c
+++ b/libavcodec/aacsbr_template.c
@@ -1041,6 +1041,7 @@ static unsigned int read_sbr_data(AACContext *ac, SpectralBandReplication *sbr,
unsigned int cnt = get_bits_count(gb);
sbr->id_aac = id_aac;
+ sbr->start = 2;
if (id_aac == TYPE_SCE || id_aac == TYPE_CCE) {
if (read_sbr_single_channel_element(ac, sbr, gb)) {
@@ -1476,6 +1477,12 @@ void AAC_RENAME(ff_sbr_apply)(AACContext *ac, SpectralBandReplication *sbr, int
sbr_turnoff(sbr);
}
+ if (sbr->start == 1) {
+ av_log(ac->avctx, AV_LOG_ERROR,
+ "No quantized data read for sbr_dequant.\n");
+ sbr_turnoff(sbr);
+ }
+
if (!sbr->kx_and_m_pushed) {
sbr->kx[0] = sbr->kx[1];
sbr->m[0] = sbr->m[1];
@@ -1485,6 +1492,7 @@ void AAC_RENAME(ff_sbr_apply)(AACContext *ac, SpectralBandReplication *sbr, int
if (sbr->start) {
sbr_dequant(sbr, id_aac);
+ sbr->start = 1;
}
for (ch = 0; ch < nch; ch++) {
/* decode channel */
--
2.6.2
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