ref: ed8e1b49370e39b776930918e5d5f7d6408c1a3c
parent: 63c325acf69cd2eba047c8577754a2e2cd2aa37e
author: Jean-Marc Valin <[email protected]>
date: Thu Jul 8 09:10:28 EDT 2010
Support for 10ms frame size
--- a/doc/draft-valin-codec-prototype.xml
+++ b/doc/draft-valin-codec-prototype.xml
@@ -115,11 +115,11 @@
repositories (for SILK and CELT). Some snapshots are provided for
convenience at <eref target='http://people.xiph.org/~jm/ietfcodec/'/> along
with sample files.
-Although the build system is very primitive
-(and inconsistent), some instructions are provided in the toplevel README file.
+Although the build system is very primitive, some instructions are provided
+in the toplevel README file.
This is very early development so both the quality and feature set should
-greatly improve over time. In the current version, only 48 kHz audio with 20 ms
-frames are supported, but support for all configurations listed in
+greatly improve over time. In the current version, only 48 kHz audio is
+supported, but support for all configurations listed in
<xref target="modes"></xref> is planned.
</t>
</section>
@@ -176,11 +176,13 @@
indicate the mode, frame size and sampling rate (MFS). This leaves 3 bits for the number of frames per packets (codes 0 to 7):
<list style="symbols">
<t>0-2: 1-3 frames in the packet, each with equal compressed size</t>
-<t>3: arbitrary number of frames in the packet, each with equal compressed size (size needs to be signalled)</t>
+<t>3: arbitrary number of frames in the packet, each with equal compressed size (one size needs to be encoded)</t>
<t>4-5: 2-3 frames in the packet, with different compressed sizes, which need to be encoded (except the last one)</t>
<t>6: arbitrary number of frames in the packet, with different compressed sizes, each of which needs to be encoded</t>
-<t>7: The first frame has this MFS, but others have different MFS. Compressed sizes need to be encoded.</t>
+<t>7: The first frame has this MFS, but others have different MFS. Each compressed size needs to be encoded.</t>
</list>
+When code 7 is used and the last frames of a packet have the same MFS, it is
+allowed to switch to another code for them.
</t>
<t>
@@ -248,7 +250,7 @@
</t>
<t>
-Three frames of different *durations*:
+Three frames of different <spanx style="emph">durations</spanx>:
</t>
@@ -273,9 +275,14 @@
<section anchor="security" title="Security Considerations">
<t>
-The codec needs to take appropriate
-security considerations into account, for example as outlined in
-<xref target="DOS"/> and <xref target="SECGUIDE"/>.
+The codec needs to take appropriate security considerations
+into account, as outlined in <xref target="DOS"/> and <xref target="SECGUIDE"/>.
+It is extremely important for the decoder to be robust against malicious
+payloads. Malicious payloads must not cause the decoder to overrun its
+allocated memory or to take much more resources to decode. Although problems
+in encoders are typically rarer, the same applies to the encoder. Malicious
+audio stream must not cause the encoder to misbehave because this would
+allow an attacker to attack transcoding gateways.
</t>
</section>
--- a/src/hybrid_decoder.c
+++ b/src/hybrid_decoder.c
@@ -94,7 +94,7 @@
/* Handle error */
}
} else {- for (i=0;i<960;i++)
+ for (i=0;i<frame_size;i++)
pcm[i] = 0;
}
@@ -110,7 +110,7 @@
{/* Encode high band with CELT */
celt_ret = celt_decode_with_ec(st->celt_dec, data, len, pcm_celt, frame_size, &dec);
- for (i=0;i<960;i++)
+ for (i=0;i<frame_size;i++)
pcm[i] += pcm_celt[i];
}
return celt_ret;
--- a/src/hybrid_encoder.c
+++ b/src/hybrid_encoder.c
@@ -97,9 +97,10 @@
if (st->mode != MODE_CELT_ONLY)
{st->encControl.bitRate = (bytes_per_packet*50*8+6000)/2;
+ st->encControl.packetSize = frame_size;
/* Call SILK encoder for the low band */
nBytes = bytes_per_packet;
- ret = SKP_Silk_SDK_Encode( st->silk_enc, &st->encControl, pcm, 960, &enc, &nBytes );
+ ret = SKP_Silk_SDK_Encode( st->silk_enc, &st->encControl, pcm, frame_size, &enc, &nBytes );
if( ret ) {fprintf (stderr, "SILK encode error\n");
/* Handle error */
@@ -121,7 +122,7 @@
for (i=0;i<ENCODER_DELAY_COMPENSATION;i++)
buf[i] = st->delay_buffer[i];
- for (;i<960;i++)
+ for (;i<frame_size;i++)
buf[i] = pcm[i-ENCODER_DELAY_COMPENSATION];
celt_encoder_ctl(st->celt_enc, CELT_SET_PREDICTION(1));
@@ -129,7 +130,7 @@
/* FIXME: Do some delay compensation here */
ret = celt_encode_with_ec(st->celt_enc, buf, NULL, frame_size, data, bytes_per_packet, &enc);
for (i=0;i<ENCODER_DELAY_COMPENSATION;i++)
- st->delay_buffer[i] = pcm[960-ENCODER_DELAY_COMPENSATION+i];
+ st->delay_buffer[i] = pcm[frame_size-ENCODER_DELAY_COMPENSATION+i];
} else {ec_enc_done(&enc);
}