libavcodec/opus.c - nest-android-app/ffmpeg - Git at Google

 /*
  * Copyright (c) 2012 Andrew D'Addesio
  * Copyright (c) 2013-2014 Mozilla Corporation
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 /**
  * @file
  * Opus decoder/parser shared code
  */

 #include <stdint.h>

 #include "libavutil/error.h"
 #include "libavutil/internal.h"

 #include "opus.h"
 #include "vorbis.h"

 static const uint16_t opus_frame_duration[32] = {
     480, 960, 1920, 2880,
     480, 960, 1920, 2880,
     480, 960, 1920, 2880,
     480, 960,
     480, 960,
     120, 240,  480,  960,
     120, 240,  480,  960,
     120, 240,  480,  960,
     120, 240,  480,  960,
 };

 /**
  * Read a 1- or 2-byte frame length
  */
 static inline int xiph_lacing_16bit(const uint8_t **ptr, const uint8_t *end)
 {
     int val;

     if (*ptr >= end)
         return AVERROR_INVALIDDATA;
     val = *(*ptr)++;
     if (val >= 252) {
         if (*ptr >= end)
             return AVERROR_INVALIDDATA;
         val += 4 * *(*ptr)++;
     }
     return val;
 }

 /**
  * Read a multi-byte length (used for code 3 packet padding size)
  */
 static inline int xiph_lacing_full(const uint8_t **ptr, const uint8_t *end)
 {
     int val = 0;
     int next;

     while (1) {
         if (*ptr >= end || val > INT_MAX - 254)
             return AVERROR_INVALIDDATA;
         next = *(*ptr)++;
         val += next;
         if (next < 255)
             break;
         else
             val--;
     }
     return val;
 }

 /**
  * Parse Opus packet info from raw packet data
  */
 int ff_opus_parse_packet(OpusPacket *pkt, const uint8_t *buf, int buf_size,
                          int self_delimiting)
 {
     const uint8_t *ptr = buf;
     const uint8_t *end = buf + buf_size;
     int padding = 0;
     int frame_bytes, i;

     if (buf_size < 1)
         goto fail;

     /* TOC byte */
     i = *ptr++;
     pkt->code   = (i     ) & 0x3;
     pkt->stereo = (i >> 2) & 0x1;
     pkt->config = (i >> 3) & 0x1F;

     /* code 2 and code 3 packets have at least 1 byte after the TOC */
     if (pkt->code >= 2 && buf_size < 2)
         goto fail;

     switch (pkt->code) {
     case 0:
         /* 1 frame */
         pkt->frame_count = 1;
         pkt->vbr         = 0;

         if (self_delimiting) {
             int len = xiph_lacing_16bit(&ptr, end);
             if (len < 0 || len > end - ptr)
                 goto fail;
             end      = ptr + len;
             buf_size = end - buf;
         }

         frame_bytes = end - ptr;
         if (frame_bytes > MAX_FRAME_SIZE)
             goto fail;
         pkt->frame_offset[0] = ptr - buf;
         pkt->frame_size[0]   = frame_bytes;
         break;
     case 1:
         /* 2 frames, equal size */
         pkt->frame_count = 2;
         pkt->vbr         = 0;

         if (self_delimiting) {
             int len = xiph_lacing_16bit(&ptr, end);
             if (len < 0 || 2 * len > end - ptr)
                 goto fail;
             end      = ptr + 2 * len;
             buf_size = end - buf;
         }

         frame_bytes = end - ptr;
         if (frame_bytes & 1 || frame_bytes >> 1 > MAX_FRAME_SIZE)
             goto fail;
         pkt->frame_offset[0] = ptr - buf;
         pkt->frame_size[0]   = frame_bytes >> 1;
         pkt->frame_offset[1] = pkt->frame_offset[0] + pkt->frame_size[0];
         pkt->frame_size[1]   = frame_bytes >> 1;
         break;
     case 2:
         /* 2 frames, different sizes */
         pkt->frame_count = 2;
         pkt->vbr         = 1;

         /* read 1st frame size */
         frame_bytes = xiph_lacing_16bit(&ptr, end);
         if (frame_bytes < 0)
             goto fail;

         if (self_delimiting) {
             int len = xiph_lacing_16bit(&ptr, end);
             if (len < 0 || len + frame_bytes > end - ptr)
                 goto fail;
             end      = ptr + frame_bytes + len;
             buf_size = end - buf;
         }

         pkt->frame_offset[0] = ptr - buf;
         pkt->frame_size[0]   = frame_bytes;

         /* calculate 2nd frame size */
         frame_bytes = end - ptr - pkt->frame_size[0];
         if (frame_bytes < 0 || frame_bytes > MAX_FRAME_SIZE)
             goto fail;
         pkt->frame_offset[1] = pkt->frame_offset[0] + pkt->frame_size[0];
         pkt->frame_size[1]   = frame_bytes;
         break;
     case 3:
         /* 1 to 48 frames, can be different sizes */
         i = *ptr++;
         pkt->frame_count = (i     ) & 0x3F;
         padding          = (i >> 6) & 0x01;
         pkt->vbr         = (i >> 7) & 0x01;

         if (pkt->frame_count == 0 || pkt->frame_count > MAX_FRAMES)
             goto fail;

         /* read padding size */
         if (padding) {
             padding = xiph_lacing_full(&ptr, end);
             if (padding < 0)
                 goto fail;
         }

         /* read frame sizes */
         if (pkt->vbr) {
             /* for VBR, all frames except the final one have their size coded
                in the bitstream. the last frame size is implicit. */
             int total_bytes = 0;
             for (i = 0; i < pkt->frame_count - 1; i++) {
                 frame_bytes = xiph_lacing_16bit(&ptr, end);
                 if (frame_bytes < 0)
                     goto fail;
                 pkt->frame_size[i] = frame_bytes;
                 total_bytes += frame_bytes;
             }

             if (self_delimiting) {
                 int len = xiph_lacing_16bit(&ptr, end);
                 if (len < 0 || len + total_bytes + padding > end - ptr)
                     goto fail;
                 end      = ptr + total_bytes + len + padding;
                 buf_size = end - buf;
             }

             frame_bytes = end - ptr - padding;
             if (total_bytes > frame_bytes)
                 goto fail;
             pkt->frame_offset[0] = ptr - buf;
             for (i = 1; i < pkt->frame_count; i++)
                 pkt->frame_offset[i] = pkt->frame_offset[i-1] + pkt->frame_size[i-1];
             pkt->frame_size[pkt->frame_count-1] = frame_bytes - total_bytes;
         } else {
             /* for CBR, the remaining packet bytes are divided evenly between
                the frames */
             if (self_delimiting) {
                 frame_bytes = xiph_lacing_16bit(&ptr, end);
                 if (frame_bytes < 0 || pkt->frame_count * frame_bytes + padding > end - ptr)
                     goto fail;
                 end      = ptr + pkt->frame_count * frame_bytes + padding;
                 buf_size = end - buf;
             } else {
                 frame_bytes = end - ptr - padding;
                 if (frame_bytes % pkt->frame_count ||
                     frame_bytes / pkt->frame_count > MAX_FRAME_SIZE)
                     goto fail;
                 frame_bytes /= pkt->frame_count;
             }

             pkt->frame_offset[0] = ptr - buf;
             pkt->frame_size[0]   = frame_bytes;
             for (i = 1; i < pkt->frame_count; i++) {
                 pkt->frame_offset[i] = pkt->frame_offset[i-1] + pkt->frame_size[i-1];
                 pkt->frame_size[i]   = frame_bytes;
             }
         }
     }

     pkt->packet_size = buf_size;
     pkt->data_size   = pkt->packet_size - padding;

     /* total packet duration cannot be larger than 120ms */
     pkt->frame_duration = opus_frame_duration[pkt->config];
     if (pkt->frame_duration * pkt->frame_count > MAX_PACKET_DUR)
         goto fail;

     /* set mode and bandwidth */
     if (pkt->config < 12) {
         pkt->mode = OPUS_MODE_SILK;
         pkt->bandwidth = pkt->config >> 2;
     } else if (pkt->config < 16) {
         pkt->mode = OPUS_MODE_HYBRID;
         pkt->bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND + (pkt->config >= 14);
     } else {
         pkt->mode = OPUS_MODE_CELT;
         pkt->bandwidth = (pkt->config - 16) >> 2;
         /* skip mediumband */
         if (pkt->bandwidth)
             pkt->bandwidth++;
     }

     return 0;

 fail:
     memset(pkt, 0, sizeof(*pkt));
     return AVERROR_INVALIDDATA;
 }

 static int channel_reorder_vorbis(int nb_channels, int channel_idx)
 {
     return ff_vorbis_channel_layout_offsets[nb_channels - 1][channel_idx];
 }

 static int channel_reorder_unknown(int nb_channels, int channel_idx)
 {
     return channel_idx;
 }

 av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
                                     OpusContext *s)
 {
     static const uint8_t default_channel_map[2] = { 0, 1 };

     int (*channel_reorder)(int, int) = channel_reorder_unknown;

     const uint8_t *extradata, *channel_map;
     int extradata_size;
     int version, channels, map_type, streams, stereo_streams, i, j;
     uint64_t layout;

     if (!avctx->extradata) {
         if (avctx->channels > 2) {
             av_log(avctx, AV_LOG_ERROR,
                    "Multichannel configuration without extradata.\n");
             return AVERROR(EINVAL);
         }
         extradata      = opus_default_extradata;
         extradata_size = sizeof(opus_default_extradata);
     } else {
         extradata = avctx->extradata;
         extradata_size = avctx->extradata_size;
     }

     if (extradata_size < 19) {
         av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
                extradata_size);
         return AVERROR_INVALIDDATA;
     }

     version = extradata[8];
     if (version > 15) {
         avpriv_request_sample(avctx, "Extradata version %d", version);
         return AVERROR_PATCHWELCOME;
     }

     avctx->delay = AV_RL16(extradata + 10);

     channels = avctx->extradata ? extradata[9] : (avctx->channels == 1) ? 1 : 2;
     if (!channels) {
         av_log(avctx, AV_LOG_ERROR, "Zero channel count specified in the extadata\n");
         return AVERROR_INVALIDDATA;
     }

     s->gain_i = AV_RL16(extradata + 16);
     if (s->gain_i)
         s->gain = ff_exp10(s->gain_i / (20.0 * 256));

     map_type = extradata[18];
     if (!map_type) {
         if (channels > 2) {
             av_log(avctx, AV_LOG_ERROR,
                    "Channel mapping 0 is only specified for up to 2 channels\n");
             return AVERROR_INVALIDDATA;
         }
         layout         = (channels == 1) ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;
         streams        = 1;
         stereo_streams = channels - 1;
         channel_map    = default_channel_map;
     } else if (map_type == 1 || map_type == 255) {
         if (extradata_size < 21 + channels) {
             av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
                    extradata_size);
             return AVERROR_INVALIDDATA;
         }

         streams        = extradata[19];
         stereo_streams = extradata[20];
         if (!streams || stereo_streams > streams ||
             streams + stereo_streams > 255) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid stream/stereo stream count: %d/%d\n", streams, stereo_streams);
             return AVERROR_INVALIDDATA;
         }

         if (map_type == 1) {
             if (channels > 8) {
                 av_log(avctx, AV_LOG_ERROR,
                        "Channel mapping 1 is only specified for up to 8 channels\n");
                 return AVERROR_INVALIDDATA;
             }
             layout = ff_vorbis_channel_layouts[channels - 1];
             channel_reorder = channel_reorder_vorbis;
         } else
             layout = 0;

         channel_map = extradata + 21;
     } else {
         avpriv_request_sample(avctx, "Mapping type %d", map_type);
         return AVERROR_PATCHWELCOME;
     }

     s->channel_maps = av_mallocz_array(channels, sizeof(*s->channel_maps));
     if (!s->channel_maps)
         return AVERROR(ENOMEM);

     for (i = 0; i < channels; i++) {
         ChannelMap *map = &s->channel_maps[i];
         uint8_t     idx = channel_map[channel_reorder(channels, i)];

         if (idx == 255) {
             map->silence = 1;
             continue;
         } else if (idx >= streams + stereo_streams) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid channel map for output channel %d: %d\n", i, idx);
             return AVERROR_INVALIDDATA;
         }

         /* check that we din't see this index yet */
         map->copy = 0;
         for (j = 0; j < i; j++)
             if (channel_map[channel_reorder(channels, j)] == idx) {
                 map->copy     = 1;
                 map->copy_idx = j;
                 break;
             }

         if (idx < 2 * stereo_streams) {
             map->stream_idx  = idx / 2;
             map->channel_idx = idx & 1;
         } else {
             map->stream_idx  = idx - stereo_streams;
             map->channel_idx = 0;
         }
     }

     avctx->channels       = channels;
     avctx->channel_layout = layout;
     s->nb_streams         = streams;
     s->nb_stereo_streams  = stereo_streams;

     return 0;
 }
	/*
	* Copyright (c) 2012 Andrew D'Addesio
	* Copyright (c) 2013-2014 Mozilla Corporation
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	/**
	* @file
	* Opus decoder/parser shared code
	*/

	#include <stdint.h>

	#include "libavutil/error.h"
	#include "libavutil/internal.h"

	#include "opus.h"
	#include "vorbis.h"

	static const uint16_t opus_frame_duration[32] = {
	480, 960, 1920, 2880,
	480, 960, 1920, 2880,
	480, 960, 1920, 2880,
	480, 960,
	480, 960,
	120, 240, 480, 960,
	120, 240, 480, 960,
	120, 240, 480, 960,
	120, 240, 480, 960,
	};

	/**
	* Read a 1- or 2-byte frame length
	*/
	static inline int xiph_lacing_16bit(const uint8_t *ptr, const uint8_t end)
	{
	int val;

	if (*ptr >= end)
	return AVERROR_INVALIDDATA;
	val = (ptr)++;
	if (val >= 252) {
	if (*ptr >= end)
	return AVERROR_INVALIDDATA;
	val += 4 * (ptr)++;
	}
	return val;
	}

	/**
	* Read a multi-byte length (used for code 3 packet padding size)
	*/
	static inline int xiph_lacing_full(const uint8_t *ptr, const uint8_t end)
	{
	int val = 0;
	int next;

	while (1) {
	if (*ptr >= end \|\| val > INT_MAX - 254)
	return AVERROR_INVALIDDATA;
	next = (ptr)++;
	val += next;
	if (next < 255)
	break;
	else
	val--;
	}
	return val;
	}

	/**
	* Parse Opus packet info from raw packet data
	*/
	int ff_opus_parse_packet(OpusPacket pkt, const uint8_t buf, int buf_size,
	int self_delimiting)
	{
	const uint8_t *ptr = buf;
	const uint8_t *end = buf + buf_size;
	int padding = 0;
	int frame_bytes, i;

	if (buf_size < 1)
	goto fail;

	/* TOC byte */
	i = *ptr++;
	pkt->code = (i ) & 0x3;
	pkt->stereo = (i >> 2) & 0x1;
	pkt->config = (i >> 3) & 0x1F;

	/* code 2 and code 3 packets have at least 1 byte after the TOC */
	if (pkt->code >= 2 && buf_size < 2)
	goto fail;

	switch (pkt->code) {
	case 0:
	/* 1 frame */
	pkt->frame_count = 1;
	pkt->vbr = 0;

	if (self_delimiting) {
	int len = xiph_lacing_16bit(&ptr, end);
	if (len < 0 \|\| len > end - ptr)
	goto fail;
	end = ptr + len;
	buf_size = end - buf;
	}

	frame_bytes = end - ptr;
	if (frame_bytes > MAX_FRAME_SIZE)
	goto fail;
	pkt->frame_offset[0] = ptr - buf;
	pkt->frame_size[0] = frame_bytes;
	break;
	case 1:
	/* 2 frames, equal size */
	pkt->frame_count = 2;
	pkt->vbr = 0;

	if (self_delimiting) {
	int len = xiph_lacing_16bit(&ptr, end);
	if (len < 0 \|\| 2 * len > end - ptr)
	goto fail;
	end = ptr + 2 * len;
	buf_size = end - buf;
	}

	frame_bytes = end - ptr;
	if (frame_bytes & 1 \|\| frame_bytes >> 1 > MAX_FRAME_SIZE)
	goto fail;
	pkt->frame_offset[0] = ptr - buf;
	pkt->frame_size[0] = frame_bytes >> 1;
	pkt->frame_offset[1] = pkt->frame_offset[0] + pkt->frame_size[0];
	pkt->frame_size[1] = frame_bytes >> 1;
	break;
	case 2:
	/* 2 frames, different sizes */
	pkt->frame_count = 2;
	pkt->vbr = 1;

	/* read 1st frame size */
	frame_bytes = xiph_lacing_16bit(&ptr, end);
	if (frame_bytes < 0)
	goto fail;

	if (self_delimiting) {
	int len = xiph_lacing_16bit(&ptr, end);
	if (len < 0 \|\| len + frame_bytes > end - ptr)
	goto fail;
	end = ptr + frame_bytes + len;
	buf_size = end - buf;
	}

	pkt->frame_offset[0] = ptr - buf;
	pkt->frame_size[0] = frame_bytes;

	/* calculate 2nd frame size */
	frame_bytes = end - ptr - pkt->frame_size[0];
	if (frame_bytes < 0 \|\| frame_bytes > MAX_FRAME_SIZE)
	goto fail;
	pkt->frame_offset[1] = pkt->frame_offset[0] + pkt->frame_size[0];
	pkt->frame_size[1] = frame_bytes;
	break;
	case 3:
	/* 1 to 48 frames, can be different sizes */
	i = *ptr++;
	pkt->frame_count = (i ) & 0x3F;
	padding = (i >> 6) & 0x01;
	pkt->vbr = (i >> 7) & 0x01;

	if (pkt->frame_count == 0 \|\| pkt->frame_count > MAX_FRAMES)
	goto fail;

	/* read padding size */
	if (padding) {
	padding = xiph_lacing_full(&ptr, end);
	if (padding < 0)
	goto fail;
	}

	/* read frame sizes */
	if (pkt->vbr) {
	/* for VBR, all frames except the final one have their size coded
	in the bitstream. the last frame size is implicit. */
	int total_bytes = 0;
	for (i = 0; i < pkt->frame_count - 1; i++) {
	frame_bytes = xiph_lacing_16bit(&ptr, end);
	if (frame_bytes < 0)
	goto fail;
	pkt->frame_size[i] = frame_bytes;
	total_bytes += frame_bytes;
	}

	if (self_delimiting) {
	int len = xiph_lacing_16bit(&ptr, end);
	if (len < 0 \|\| len + total_bytes + padding > end - ptr)
	goto fail;
	end = ptr + total_bytes + len + padding;
	buf_size = end - buf;
	}

	frame_bytes = end - ptr - padding;
	if (total_bytes > frame_bytes)
	goto fail;
	pkt->frame_offset[0] = ptr - buf;
	for (i = 1; i < pkt->frame_count; i++)
	pkt->frame_offset[i] = pkt->frame_offset[i-1] + pkt->frame_size[i-1];
	pkt->frame_size[pkt->frame_count-1] = frame_bytes - total_bytes;
	} else {
	/* for CBR, the remaining packet bytes are divided evenly between
	the frames */
	if (self_delimiting) {
	frame_bytes = xiph_lacing_16bit(&ptr, end);
	if (frame_bytes < 0 \|\| pkt->frame_count * frame_bytes + padding > end - ptr)
	goto fail;
	end = ptr + pkt->frame_count * frame_bytes + padding;
	buf_size = end - buf;
	} else {
	frame_bytes = end - ptr - padding;
	if (frame_bytes % pkt->frame_count \|\|
	frame_bytes / pkt->frame_count > MAX_FRAME_SIZE)
	goto fail;
	frame_bytes /= pkt->frame_count;
	}

	pkt->frame_offset[0] = ptr - buf;
	pkt->frame_size[0] = frame_bytes;
	for (i = 1; i < pkt->frame_count; i++) {
	pkt->frame_offset[i] = pkt->frame_offset[i-1] + pkt->frame_size[i-1];
	pkt->frame_size[i] = frame_bytes;
	}
	}
	}

	pkt->packet_size = buf_size;
	pkt->data_size = pkt->packet_size - padding;

	/* total packet duration cannot be larger than 120ms */
	pkt->frame_duration = opus_frame_duration[pkt->config];
	if (pkt->frame_duration * pkt->frame_count > MAX_PACKET_DUR)
	goto fail;

	/* set mode and bandwidth */
	if (pkt->config < 12) {
	pkt->mode = OPUS_MODE_SILK;
	pkt->bandwidth = pkt->config >> 2;
	} else if (pkt->config < 16) {
	pkt->mode = OPUS_MODE_HYBRID;
	pkt->bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND + (pkt->config >= 14);
	} else {
	pkt->mode = OPUS_MODE_CELT;
	pkt->bandwidth = (pkt->config - 16) >> 2;
	/* skip mediumband */
	if (pkt->bandwidth)
	pkt->bandwidth++;
	}

	return 0;

	fail:
	memset(pkt, 0, sizeof(*pkt));
	return AVERROR_INVALIDDATA;
	}

	static int channel_reorder_vorbis(int nb_channels, int channel_idx)
	{
	return ff_vorbis_channel_layout_offsets[nb_channels - 1][channel_idx];
	}

	static int channel_reorder_unknown(int nb_channels, int channel_idx)
	{
	return channel_idx;
	}

	av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
	OpusContext *s)
	{
	static const uint8_t default_channel_map[2] = { 0, 1 };

	int (*channel_reorder)(int, int) = channel_reorder_unknown;

	const uint8_t extradata, channel_map;
	int extradata_size;
	int version, channels, map_type, streams, stereo_streams, i, j;
	uint64_t layout;

	if (!avctx->extradata) {
	if (avctx->channels > 2) {
	av_log(avctx, AV_LOG_ERROR,
	"Multichannel configuration without extradata.\n");
	return AVERROR(EINVAL);
	}
	extradata = opus_default_extradata;
	extradata_size = sizeof(opus_default_extradata);
	} else {
	extradata = avctx->extradata;
	extradata_size = avctx->extradata_size;
	}

	if (extradata_size < 19) {
	av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
	extradata_size);
	return AVERROR_INVALIDDATA;
	}

	version = extradata[8];
	if (version > 15) {
	avpriv_request_sample(avctx, "Extradata version %d", version);
	return AVERROR_PATCHWELCOME;
	}

	avctx->delay = AV_RL16(extradata + 10);

	channels = avctx->extradata ? extradata[9] : (avctx->channels == 1) ? 1 : 2;
	if (!channels) {
	av_log(avctx, AV_LOG_ERROR, "Zero channel count specified in the extadata\n");
	return AVERROR_INVALIDDATA;
	}

	s->gain_i = AV_RL16(extradata + 16);
	if (s->gain_i)
	s->gain = ff_exp10(s->gain_i / (20.0 * 256));

	map_type = extradata[18];
	if (!map_type) {
	if (channels > 2) {
	av_log(avctx, AV_LOG_ERROR,
	"Channel mapping 0 is only specified for up to 2 channels\n");
	return AVERROR_INVALIDDATA;
	}
	layout = (channels == 1) ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;
	streams = 1;
	stereo_streams = channels - 1;
	channel_map = default_channel_map;
	} else if (map_type == 1 \|\| map_type == 255) {
	if (extradata_size < 21 + channels) {
	av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
	extradata_size);
	return AVERROR_INVALIDDATA;
	}

	streams = extradata[19];
	stereo_streams = extradata[20];
	if (!streams \|\| stereo_streams > streams \|\|
	streams + stereo_streams > 255) {
	av_log(avctx, AV_LOG_ERROR,
	"Invalid stream/stereo stream count: %d/%d\n", streams, stereo_streams);
	return AVERROR_INVALIDDATA;
	}

	if (map_type == 1) {
	if (channels > 8) {
	av_log(avctx, AV_LOG_ERROR,
	"Channel mapping 1 is only specified for up to 8 channels\n");
	return AVERROR_INVALIDDATA;
	}
	layout = ff_vorbis_channel_layouts[channels - 1];
	channel_reorder = channel_reorder_vorbis;
	} else
	layout = 0;

	channel_map = extradata + 21;
	} else {
	avpriv_request_sample(avctx, "Mapping type %d", map_type);
	return AVERROR_PATCHWELCOME;
	}

	s->channel_maps = av_mallocz_array(channels, sizeof(*s->channel_maps));
	if (!s->channel_maps)
	return AVERROR(ENOMEM);

	for (i = 0; i < channels; i++) {
	ChannelMap *map = &s->channel_maps[i];
	uint8_t idx = channel_map[channel_reorder(channels, i)];

	if (idx == 255) {
	map->silence = 1;
	continue;
	} else if (idx >= streams + stereo_streams) {
	av_log(avctx, AV_LOG_ERROR,
	"Invalid channel map for output channel %d: %d\n", i, idx);
	return AVERROR_INVALIDDATA;
	}

	/* check that we din't see this index yet */
	map->copy = 0;
	for (j = 0; j < i; j++)
	if (channel_map[channel_reorder(channels, j)] == idx) {
	map->copy = 1;
	map->copy_idx = j;
	break;
	}

	if (idx < 2 * stereo_streams) {
	map->stream_idx = idx / 2;
	map->channel_idx = idx & 1;
	} else {
	map->stream_idx = idx - stereo_streams;
	map->channel_idx = 0;
	}
	}

	avctx->channels = channels;
	avctx->channel_layout = layout;
	s->nb_streams = streams;
	s->nb_stereo_streams = stereo_streams;

	return 0;
	}