[paraslash.git] / fecdec_filter.c

/*
 * Copyright (C) 2009-2011 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file fecdec_filter.c A filter that fec-decodes an audio stream. */

#include <regex.h>
#include <stdbool.h>

#include <dirent.h>
#include "para.h"
#include "error.h"
#include "list.h"
#include "sched.h"
#include "ggo.h"
#include "buffer_tree.h"
#include "filter.h"
#include "string.h"
#include "portable_io.h"
#include "fec.h"
#include "fd.h"

/**
 * How many FEC groups to store in memory.
 *
 * Packet reordering requires to keep more than one FEC group in memory because
 * slices belonging to the next FEC group may arrive before the current FEC group
 * is complete.
 */
#define NUM_FEC_GROUPS 3

/** Data read from the header of a slice. */
struct fec_header {
        /** Total number of slices in this group. */
        uint8_t slices_per_group;
        /** Number of slices needed to start decoding. */
        uint8_t data_slices_per_group;
        /** Size of the ogg vorbis/wma header (zero for mp3, aac). */
        uint32_t audio_header_size;
        /** Number of the FEC group this slice belongs to. */
        uint32_t group_num;
        /** Size of the data in this FEC group. */
        uint32_t group_bytes;
        /** Number of this slice in the group. */
        uint8_t slice_num;
        /** Used data bytes of this slice. */
        uint16_t slice_bytes;
        /** Non-zero if this group is the beginning of the stream. */
        uint8_t bos;
        /** Non-zero if this stream embedds audio headers into fec groups. */
        uint8_t header_stream;
};

/**
 * The status of one partially received FEC group.
 */
struct fecdec_group {
        /** The header read from the last slice. */
        struct fec_header h;
        /** How many slices received so far. */
        int num_received_slices;
        /** Bitmap of received slices. */
        uint8_t received_slices[32];
        /** The size of the \a idx and the \a data arrays below. */
        int num_slices;
        /** Array of indices of the received slices. */
        int *idx;
        /** Content of the received slices. */
        unsigned char **data;
};

/**
 * Data private to the fecdec filter.
 */
struct private_fecdec_data {
        /** Used by the fec core code. */
        struct fec_parms *fec;
        /** Keeps track of what was received so far. */
        struct fecdec_group groups[NUM_FEC_GROUPS];
        /** Whether an audio file header was already received. */
        int have_header;
        /** Points to the first received group. */
        struct fecdec_group *first_complete_group;
        struct btr_pool *btrp;
};

/** Iterate over all fecdec groups. */
#define FOR_EACH_FECDEC_GROUP(g, d) for (g = (d)->groups; \
        (g) < (d)->groups + NUM_FEC_GROUPS; (g)++)

static int group_complete(struct fecdec_group *fg)
{
        return fg->num_received_slices >= fg->h.data_slices_per_group;
}

static int group_empty(struct fecdec_group *fg)
{
        return fg->num_received_slices == 0;
}

static void clear_group(struct fecdec_group *fg)
{
        int i;

        for (i = 0; i < fg->num_slices; i++)
                free(fg->data[i]);
        free(fg->data);
        free(fg->idx);
        memset(fg, 0, sizeof(*fg));
}

static int find_group(struct fec_header *h,
                struct private_fecdec_data *pfd, struct fecdec_group **result)
{
        struct fecdec_group *fg;

        FOR_EACH_FECDEC_GROUP(fg, pfd) {
                if (fg->h.group_num != h->group_num)
                        continue;
                if (fg->num_received_slices == 0)
                        goto success;
                if (fg->h.slices_per_group != h->slices_per_group)
                        return -E_BAD_FEC_HEADER;
                if (fg->h.data_slices_per_group != h->data_slices_per_group)
                        return -E_BAD_FEC_HEADER;
                if (fg->h.group_bytes != h->group_bytes)
                        return -E_BAD_FEC_HEADER;
success:
                *result = fg;
                return 1;
        }
        return 0;
}

static struct fecdec_group *find_unused_group(struct private_fecdec_data *pfd)
{
        struct fecdec_group *fg;

        FOR_EACH_FECDEC_GROUP(fg, pfd) {
                if (fg->num_received_slices == 0)
                        return fg;
        }
        return NULL;
}

static struct fecdec_group *try_to_free_group(struct private_fecdec_data *pfd)
{
        struct fecdec_group *fg;

        FOR_EACH_FECDEC_GROUP(fg, pfd) {
                if (!group_complete(fg))
                        continue;
                /*
                 * Don't clear the first complete group if it has not yet been
                 * decoded.
                 */
                if (fg == pfd->first_complete_group)
                        continue;
                clear_group(fg);
                return fg;
        }
        return NULL;
}

static struct fecdec_group *free_oldest_group(struct private_fecdec_data *pfd)
{
        struct fecdec_group *fg, *oldest = NULL;

        FOR_EACH_FECDEC_GROUP(fg, pfd) {
                if (!oldest || oldest->h.group_num > fg->h.group_num)
                        oldest = fg;
        }
        if (!group_complete(oldest) && !group_empty(oldest))
                PARA_WARNING_LOG("Clearing incomplete group %d "
                        "(contains %d slices)\n", oldest->h.group_num,
                        oldest->num_received_slices);
        if (oldest == pfd->first_complete_group)
                pfd->first_complete_group = NULL;
        clear_group(oldest);
        return oldest;
}

/* returns 1 if the group was found, 0 if not, negative on errors */
static int get_group(struct fec_header *h, struct private_fecdec_data *pfd,
                struct fecdec_group **result)
{
        struct fecdec_group *fg;
        int ret = find_group(h, pfd, &fg);

        if (ret < 0)
                return ret;
        if (ret > 0) /* found group */
                goto success;
        /* group not found */
        fg = find_unused_group(pfd);
        if (fg)
                goto success;
        fg = try_to_free_group(pfd);
        if (fg)
                goto success;
        fg = free_oldest_group(pfd);
        ret = 0;
success:
        fg->h = *h;
        *result = fg;
        return ret;
}

static bool test_and_set_slice_bit(struct fecdec_group *fg, uint8_t slice_num)
{
        uint8_t *p = fg->received_slices + slice_num / 8, old = *p;

        *p |= 1 << (slice_num % 8);
        return old == *p;
}

/*
 * returns 1 if slice was added, zero otherwise (because the group was already
 * complete or a slice has been received twice).
 */
static int add_slice(char *buf, struct fecdec_group *fg)
{
        int r;
        uint8_t slice_num = fg->h.slice_num;

        if (group_complete(fg)) {
                PARA_DEBUG_LOG("group %d complete, ignoring slice %d\n",
                        fg->h.group_num, slice_num);
                return 0;
        }
        if (fg->num_slices == 0) {
                fg->num_slices = fg->h.slices_per_group;
                fg->idx = para_malloc(fg->num_slices * sizeof(int));
                fg->data = para_calloc(fg->num_slices * sizeof(unsigned char *));
        }
        r = fg->num_received_slices;
        /* Check if we already have this slice. */
        if (test_and_set_slice_bit(fg, slice_num)) {
                PARA_INFO_LOG("ignoring duplicate slice %d:%d\n", fg->h.group_num,
                        slice_num);
                return 0;
        }
        fg->idx[r] = slice_num;
        fg->data[r] = para_malloc(fg->h.slice_bytes);
        memcpy(fg->data[r], buf, fg->h.slice_bytes);
        fg->num_received_slices++;
        return 1;
}

/**
 * The different states of a complete FEC group.
 *
 * Even if a FEC group has been received successfully, it probably can not be
 * used right away because some streams (ogg, wma) need to receive an audio
 * file header before decoding can start.
 */
enum fec_group_usability {
        /** Drop the group (because we did not receive the header yet). */
        FEC_GROUP_UNUSABLE,
        /** Use all data in the group. */
        FEC_GROUP_USABLE,
        /** Use the group, but drop its audio file header. */
        FEC_GROUP_USABLE_SKIP_HEADER,
        /** Use the group, including its header. */
        FEC_GROUP_USABLE_WITH_HEADER
};

static enum fec_group_usability group_is_usable(struct fecdec_group *fg,
                struct private_fecdec_data *pfd)
{
        struct fec_header *h = &fg->h;

        if (!h->header_stream)
                return FEC_GROUP_USABLE;
        if (pfd->have_header) {
                if (h->audio_header_size)
                        return FEC_GROUP_USABLE_SKIP_HEADER;
                return FEC_GROUP_USABLE;
        }
        if (fg->h.bos)
                return FEC_GROUP_USABLE;
        if (fg->h.audio_header_size)
                return FEC_GROUP_USABLE_WITH_HEADER;
        return FEC_GROUP_UNUSABLE;
}

static int decode_group(struct fecdec_group *fg, struct filter_node *fn)
{
        int i, ret, sb = fg->h.slice_bytes;
        size_t written, need;
        struct private_fecdec_data *pfd = fn->private_data;
        enum fec_group_usability u = group_is_usable(fg, pfd);
        char *buf = NULL, *p;

        if (u == FEC_GROUP_UNUSABLE) {
                PARA_INFO_LOG("dropping unusable group %d\n", fg->h.group_num);
                return 0;
        }
        PARA_DEBUG_LOG("decoding group %d (%d slices)\n", fg->h.group_num,
                fg->h.data_slices_per_group);
        ret = fec_decode(pfd->fec, fg->data, fg->idx, sb);
        if (ret < 0)
                return ret;
        pfd->have_header = 1;
        i = 0;
        if (u == FEC_GROUP_USABLE_SKIP_HEADER) {
                i = DIV_ROUND_UP(fg->h.audio_header_size, fg->h.slice_bytes);
                PARA_DEBUG_LOG("skipping %d header slices\n", i);
        }
        PARA_DEBUG_LOG("writing group %d (%d/%d decoded data bytes)\n",
                fg->h.group_num, fg->h.group_bytes,
                fg->h.data_slices_per_group * sb);
        need = (fg->h.data_slices_per_group - i) * sb;
        if (need > btr_pool_unused(pfd->btrp))
                return -E_FECDEC_OVERRUN;
        btr_pool_get_buffer(pfd->btrp, &buf);
        p = buf;
        if (u == FEC_GROUP_USABLE_WITH_HEADER) {
                PARA_INFO_LOG("writing audio file header\n");
                written = 0;
                for (i = 0; i < fg->h.data_slices_per_group; i++) {
                        size_t n = sb;
                        if (written >= fg->h.audio_header_size)
                                break;
                        if (sb + written > fg->h.audio_header_size)
                                n = fg->h.audio_header_size - written;
                        btr_copy(fg->data[i], n, pfd->btrp, fn->btrn);
                        written += n;
                }
                p += written;
        }
        written = 0;
        for (; i < fg->h.data_slices_per_group; i++) {
                size_t n = sb;
                if (n + written > fg->h.group_bytes)
                        n = fg->h.group_bytes - written;
                btr_copy(fg->data[i], n, pfd->btrp, fn->btrn);
                written += n;
        }
        p += written;
        return 0;
}

/**
 * Read a fec header from a buffer.
 *
 * \param buf The buffer to write to.
 * \param h The fec header to write.
 */
static int read_fec_header(char *buf, size_t len, struct fec_header *h)
{
        uint32_t magic;

        if (len < FEC_HEADER_SIZE)
                return 0;
        magic = read_u32(buf);
        if (magic != FEC_MAGIC)
                return -E_BAD_FEC_HEADER;
        h->slices_per_group = read_u8(buf + 4);
        h->data_slices_per_group = read_u8(buf + 5);
        h->audio_header_size = read_u32(buf + 6);

        h->group_num = read_u32(buf + 10);
        h->group_bytes = read_u32(buf + 14);

        h->slice_num = read_u8(buf + 18);
        h->slice_bytes = read_u16(buf + 20);
        h->bos = read_u8(buf + 22);
        h->header_stream = read_u8(buf + 23);
        if (!memcmp(buf, FEC_EOF_PACKET, FEC_EOF_PACKET_LEN))
                return -E_FECDEC_EOF;
//      PARA_DEBUG_LOG("group %u, slize %u, slices per group: %u\n",
//              h->group_num, h->slice_num, h->slices_per_group);
        return 1;
}

/* returns 1 if we used the buffer, 0 if we didn't, negative on errors */
static int dispatch_slice(char *buf, size_t len, struct fec_header *h,
                struct filter_node *fn)
{
        struct fecdec_group *fg;
        int ret, k, n;
        struct private_fecdec_data *pfd = fn->private_data;

        if (h->slice_bytes > len) { /* can not use the thing, try to read more */
                fn->min_iqs = h->slice_bytes + FEC_HEADER_SIZE;
                return 0;
        }
        ret = get_group(h, pfd, &fg);
        if (ret < 0)
                return ret;
        if (!add_slice(buf, fg)) /* group already complete */
                return 1;
        if (!group_complete(fg))
                return 1;
        /* this slice completed the group */
        if (pfd->fec)
                goto decode;
        /* it's either the first or the second complete group */
        if (!pfd->first_complete_group) { /* it's the first group */
                enum fec_group_usability u = group_is_usable(fg, pfd);
                assert(u != FEC_GROUP_USABLE_SKIP_HEADER);
                if (u == FEC_GROUP_UNUSABLE) /* forget it */
                        return 1;
                pfd->first_complete_group = fg; /* remember it */
                return 1;
        }
        /* we have two complete groups, let's go */
        k = h->data_slices_per_group;
        n = h->slices_per_group;
        PARA_NOTICE_LOG("init fec (%d, %d)\n", k, n);
        ret = fec_new(k, n, &pfd->fec);
        if (ret < 0)
                return ret;
        pfd->btrp = btr_pool_new("fecdec", 64 * 1024);
        /* decode and clear the first group */
        ret = decode_group(pfd->first_complete_group, fn);
        if (ret < 0)
                return ret;
        clear_group(pfd->first_complete_group);
        pfd->first_complete_group = NULL;
decode:
        ret = decode_group(fg, fn);
        if (ret < 0)
                return ret;
        return 1;
}

static void fecdec_close(struct filter_node *fn)
{
        struct private_fecdec_data *pfd = fn->private_data;
        struct fecdec_group *fg;

        FOR_EACH_FECDEC_GROUP(fg, pfd)
                clear_group(fg);
        fec_free(pfd->fec);
        btr_pool_free(pfd->btrp);
        free(fn->private_data);
        fn->private_data = NULL;
}

static void fecdec_post_select(__a_unused struct sched *s, struct task *t)
{
        struct filter_node *fn = container_of(t, struct filter_node, task);
        struct btr_node *btrn = fn->btrn;
        int ret;
        struct fec_header h;
        char *buf;
        size_t len;

next_buffer:
        ret = btr_node_status(btrn, fn->min_iqs, BTR_NT_INTERNAL);
        if (ret <= 0)
                goto out;
        btr_merge(btrn, fn->min_iqs);
        len = btr_next_buffer(btrn, &buf);
        ret = read_fec_header(buf, len, &h);
        if (ret <= 0)
                goto out;
        ret = -E_BAD_SLICE_SIZE;
        if (!h.slice_bytes)
                goto out;
        ret = -E_BAD_SLICE_NUM;
        if (h.slice_num > h.slices_per_group)
                goto out;
        ret = dispatch_slice(buf + FEC_HEADER_SIZE, len - FEC_HEADER_SIZE,
                &h, fn);
        //PARA_INFO_LOG("ret: %d, len: %d, slice_bytes: %d\n", ret, len, h.slice_bytes);
        if (ret <= 0)
                goto out;
        btr_consume(btrn, FEC_HEADER_SIZE + h.slice_bytes);
        goto next_buffer;
out:
        t->error = ret;
        if (ret < 0)
                btr_remove_node(btrn);
}

static void fecdec_open(struct filter_node *fn)
{
        struct private_fecdec_data *pfd;
        pfd = para_calloc(sizeof(*pfd));
        fn->private_data = pfd;
        fn->min_iqs = FEC_HEADER_SIZE;
}

/**
 * The init function of the fecdec filter.
 *
 * \param f Struct to initialize.
 */
void fecdec_filter_init(struct filter *f)
{
        f->close = fecdec_close;
        f->open = fecdec_open;
        f->pre_select = generic_filter_pre_select;
        f->post_select = fecdec_post_select;
}