PeerStreamer

/*

 * MOV, 3GP, MP4 muxer RTP hinting

 * Copyright (c) 2010 Martin Storsjo

 *

 * 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

 */

#include "movenc.h"

#include "libavutil/intreadwrite.h"

#include "internal.h"

int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)

{

    MOVMuxContext *mov  = s->priv_data;

    MOVTrack *track     = &mov->tracks[index];

    MOVTrack *src_track = &mov->tracks[src_index];

    AVStream *src_st    = s->streams[src_index];

    int ret = AVERROR(ENOMEM);

    AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);

    track->tag = MKTAG('r','t','p',' ');

    track->src_track = src_index;

    if (!rtp_format) {

        ret = AVERROR(ENOENT);

        goto fail;

    }

    track->enc = avcodec_alloc_context();

    if (!track->enc)

        goto fail;

    track->enc->codec_type = AVMEDIA_TYPE_DATA;

    track->enc->codec_tag  = track->tag;

    track->rtp_ctx = avformat_alloc_context();

    if (!track->rtp_ctx)

        goto fail;

    track->rtp_ctx->oformat = rtp_format;

    if (!av_new_stream(track->rtp_ctx, 0))

        goto fail;

    /* Copy stream parameters */

    track->rtp_ctx->streams[0]->sample_aspect_ratio =

                        src_st->sample_aspect_ratio;

    avcodec_copy_context(track->rtp_ctx->streams[0]->codec, src_st->codec);

    if ((ret = url_open_dyn_packet_buf(&track->rtp_ctx->pb,

                                       RTP_MAX_PACKET_SIZE)) < 0)

        goto fail;

    ret = av_write_header(track->rtp_ctx);

    if (ret)

        goto fail;

    /* Copy the RTP AVStream timebase back to the hint AVStream */

    track->timescale = track->rtp_ctx->streams[0]->time_base.den;

    /* Mark the hinted track that packets written to it should be

     * sent to this track for hinting. */

    src_track->hint_track = index;

    return 0;

fail:

    av_log(s, AV_LOG_WARNING,

           "Unable to initialize hinting of stream %d\n", src_index);

    if (track->rtp_ctx && track->rtp_ctx->pb) {

        uint8_t *buf;

        url_close_dyn_buf(track->rtp_ctx->pb, &buf);

        av_free(buf);

    }

    if (track->rtp_ctx) {

        avformat_free_context(track->rtp_ctx);

        track->rtp_ctx = NULL;

    }

    av_freep(&track->enc);

    /* Set a default timescale, to avoid crashes in dump_format */

    track->timescale = 90000;

    return ret;

}

/**

 * Remove the first sample from the sample queue.

 */

static void sample_queue_pop(HintSampleQueue *queue)

{

    if (queue->len <= 0)

        return;

    if (queue->samples[0].own_data)

        av_free(queue->samples[0].data);

    queue->len--;

    memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);

}

/**

 * Empty the sample queue, releasing all memory.

 */

static void sample_queue_free(HintSampleQueue *queue)

{

    int i;

    for (i = 0; i < queue->len; i++)

        if (queue->samples[i].own_data)

            av_free(queue->samples[i].data);

    av_freep(&queue->samples);

    queue->len = 0;

    queue->size = 0;

}

/**

 * Add a reference to the sample data to the sample queue. The data is

 * not copied. sample_queue_retain should be called before pkt->data

 * is reused/freed.

 */

static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)

{

    /* No need to keep track of smaller samples, since describing them

     * with immediates is more efficient. */

    if (pkt->size <= 14)

        return;

    if (!queue->samples || queue->len >= queue->size) {

        HintSample* samples;

        queue->size += 10;

        samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);

        if (!samples)

            return;

        queue->samples = samples;

    }

    queue->samples[queue->len].data = pkt->data;

    queue->samples[queue->len].size = pkt->size;

    queue->samples[queue->len].sample_number = sample;

    queue->samples[queue->len].offset = 0;

    queue->samples[queue->len].own_data = 0;

    queue->len++;

}

/**

 * Make local copies of all referenced sample data in the queue.

 */

static void sample_queue_retain(HintSampleQueue *queue)

{

    int i;

    for (i = 0; i < queue->len; ) {

        HintSample *sample = &queue->samples[i];

        if (!sample->own_data) {

            uint8_t* ptr = av_malloc(sample->size);

            if (!ptr) {

                /* Unable to allocate memory for this one, remove it */

                memmove(queue->samples + i, queue->samples + i + 1,

                        sizeof(HintSample)*(queue->len - i - 1));

                queue->len--;

                continue;

            }

            memcpy(ptr, sample->data, sample->size);

            sample->data = ptr;

            sample->own_data = 1;

        }

        i++;

    }

}

/**

 * Find matches of needle[n_pos ->] within haystack. If a sufficiently

 * large match is found, matching bytes before n_pos are included

 * in the match, too (within the limits of the arrays).

 *

 * @param haystack buffer that may contain parts of needle

 * @param h_len length of the haystack buffer

 * @param needle buffer containing source data that have been used to

 *               construct haystack

 * @param n_pos start position in needle used for looking for matches

 * @param n_len length of the needle buffer

 * @param match_h_offset_ptr offset of the first matching byte within haystack

 * @param match_n_offset_ptr offset of the first matching byte within needle

 * @param match_len_ptr length of the matched segment

 * @return 0 if a match was found, < 0 if no match was found

 */

static int match_segments(const uint8_t *haystack, int h_len,

                          const uint8_t *needle, int n_pos, int n_len,

                          int *match_h_offset_ptr, int *match_n_offset_ptr,

                          int *match_len_ptr)

{

    int h_pos;

    for (h_pos = 0; h_pos < h_len; h_pos++) {

        int match_len = 0;

        int match_h_pos, match_n_pos;

        /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */

        while (h_pos + match_len < h_len && n_pos + match_len < n_len &&

               needle[n_pos + match_len] == haystack[h_pos + match_len])

            match_len++;

        if (match_len <= 8)

            continue;

        /* If a sufficiently large match was found, try to expand

         * the matched segment backwards. */

        match_h_pos = h_pos;

        match_n_pos = n_pos;

        while (match_n_pos > 0 && match_h_pos > 0 &&

               needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {

            match_n_pos--;

            match_h_pos--;

            match_len++;

        }

        if (match_len <= 14)

            continue;

        *match_h_offset_ptr = match_h_pos;

        *match_n_offset_ptr = match_n_pos;

        *match_len_ptr = match_len;

        return 0;

    }

    return -1;

}

/**

 * Look for segments in samples in the sample queue matching the data

 * in ptr. Samples not matching are removed from the queue. If a match

 * is found, the next time it will look for matches starting from the

 * end of the previous matched segment.

 *

 * @param data data to find matches for in the sample queue

 * @param len length of the data buffer

 * @param queue samples used for looking for matching segments

 * @param pos the offset in data of the matched segment

 * @param match_sample the number of the sample that contained the match

 * @param match_offset the offset of the matched segment within the sample

 * @param match_len the length of the matched segment

 * @return 0 if a match was found, < 0 if no match was found

 */

static int find_sample_match(const uint8_t *data, int len,

                             HintSampleQueue *queue, int *pos,

                             int *match_sample, int *match_offset,

                             int *match_len)

{

    while (queue->len > 0) {

        HintSample *sample = &queue->samples[0];

        /* If looking for matches in a new sample, skip the first 5 bytes,

         * since they often may be modified/removed in the output packet. */

        if (sample->offset == 0 && sample->size > 5)

            sample->offset = 5;

        if (match_segments(data, len, sample->data, sample->offset,

                           sample->size, pos, match_offset, match_len) == 0) {

            *match_sample = sample->sample_number;

            /* Next time, look for matches at this offset, with a little

             * margin to this match. */

            sample->offset = *match_offset + *match_len + 5;

            if (sample->offset + 10 >= sample->size)

                sample_queue_pop(queue); /* Not enough useful data left */

            return 0;

        }

        if (sample->offset < 10 && sample->size > 20) {

            /* No match found from the start of the sample,

             * try from the middle of the sample instead. */

            sample->offset = sample->size/2;

        } else {

            /* No match for this sample, remove it */

            sample_queue_pop(queue);

        }

    }

    return -1;

}

static void output_immediate(const uint8_t *data, int size,

                             ByteIOContext *out, int *entries)

{

    while (size > 0) {

        int len = size;

        if (len > 14)

            len = 14;

        put_byte(out, 1); /* immediate constructor */

        put_byte(out, len); /* amount of valid data */

        put_buffer(out, data, len);

        data += len;

        size -= len;

        for (; len < 14; len++)

            put_byte(out, 0);

        (*entries)++;

    }

}

static void output_match(ByteIOContext *out, int match_sample,

                         int match_offset, int match_len, int *entries)

{

    put_byte(out, 2); /* sample constructor */

    put_byte(out, 0); /* track reference */

    put_be16(out, match_len);

    put_be32(out, match_sample);

    put_be32(out, match_offset);

    put_be16(out, 1); /* bytes per block */

    put_be16(out, 1); /* samples per block */

    (*entries)++;

}

static void describe_payload(const uint8_t *data, int size,

                             ByteIOContext *out, int *entries,

                             HintSampleQueue *queue)

{

    /* Describe the payload using different constructors */

    while (size > 0) {

        int match_sample, match_offset, match_len, pos;

        if (find_sample_match(data, size, queue, &pos, &match_sample,

                              &match_offset, &match_len) < 0)

            break;

        output_immediate(data, pos, out, entries);

        data += pos;

        size -= pos;

        output_match(out, match_sample, match_offset, match_len, entries);

        data += match_len;

        size -= match_len;

    }

    output_immediate(data, size, out, entries);

}

/**

 * Write an RTP hint (that may contain one or more RTP packets)

 * for the packets in data. data contains one or more packets with a

 * BE32 size header.

 *

 * @param out buffer where the hints are written

 * @param data buffer containing RTP packets

 * @param size the size of the data buffer

 * @param trk the MOVTrack for the hint track

 * @param pts pointer where the timestamp for the written RTP hint is stored

 * @return the number of RTP packets in the written hint

 */

static int write_hint_packets(ByteIOContext *out, const uint8_t *data,

                              int size, MOVTrack *trk, int64_t *pts)

{

    int64_t curpos;

    int64_t count_pos, entries_pos;

    int count = 0, entries;

    count_pos = url_ftell(out);

    /* RTPsample header */

    put_be16(out, 0); /* packet count */

    put_be16(out, 0); /* reserved */

    while (size > 4) {

        uint32_t packet_len = AV_RB32(data);

        uint16_t seq;

        uint32_t ts;

        data += 4;

        size -= 4;

        if (packet_len > size || packet_len <= 12)

            break;

        if (data[1] >= 200 && data[1] <= 204) {

            /* RTCP packet, just skip */

            data += packet_len;

            size -= packet_len;

            continue;

        }

        if (packet_len > trk->max_packet_size)

            trk->max_packet_size = packet_len;

        seq = AV_RB16(&data[2]);

        ts = AV_RB32(&data[4]);

        if (trk->prev_rtp_ts == 0)

            trk->prev_rtp_ts = ts;

        /* Unwrap the 32-bit RTP timestamp that wraps around often

         * into a not (as often) wrapping 64-bit timestamp. */

        trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);

        trk->prev_rtp_ts = ts;

        if (*pts == AV_NOPTS_VALUE)

            *pts = trk->cur_rtp_ts_unwrapped;

        count++;

        /* RTPpacket header */

        put_be32(out, 0); /* relative_time */

        put_buffer(out, data, 2); /* RTP header */

        put_be16(out, seq); /* RTPsequenceseed */

        put_be16(out, 0); /* reserved + flags */

        entries_pos = url_ftell(out);

        put_be16(out, 0); /* entry count */

        data += 12;

        size -= 12;

        packet_len -= 12;

        entries = 0;

        /* Write one or more constructors describing the payload data */

        describe_payload(data, packet_len, out, &entries, &trk->sample_queue);

        data += packet_len;

        size -= packet_len;

        curpos = url_ftell(out);

        url_fseek(out, entries_pos, SEEK_SET);

        put_be16(out, entries);

        url_fseek(out, curpos, SEEK_SET);

    }

    curpos = url_ftell(out);

    url_fseek(out, count_pos, SEEK_SET);

    put_be16(out, count);

    url_fseek(out, curpos, SEEK_SET);

    return count;

}

int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,

                             int track_index, int sample)

{

    MOVMuxContext *mov = s->priv_data;

    MOVTrack *trk = &mov->tracks[track_index];

    AVFormatContext *rtp_ctx = trk->rtp_ctx;

    uint8_t *buf = NULL;

    int size;

    ByteIOContext *hintbuf = NULL;

    AVPacket hint_pkt;

    int ret = 0, count;

    if (!rtp_ctx)

        return AVERROR(ENOENT);

    if (!rtp_ctx->pb)

        return AVERROR(ENOMEM);

    sample_queue_push(&trk->sample_queue, pkt, sample);

    /* Feed the packet to the RTP muxer */

    ff_write_chained(rtp_ctx, 0, pkt, s);

    /* Fetch the output from the RTP muxer, open a new output buffer

     * for next time. */

    size = url_close_dyn_buf(rtp_ctx->pb, &buf);

    if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,

                                       RTP_MAX_PACKET_SIZE)) < 0)

        goto done;

    if (size <= 0)

        goto done;

    /* Open a buffer for writing the hint */

    if ((ret = url_open_dyn_buf(&hintbuf)) < 0)

        goto done;

    av_init_packet(&hint_pkt);

    count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);

    av_freep(&buf);

    /* Write the hint data into the hint track */

    hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);

    hint_pkt.data = buf;

    hint_pkt.pts  = hint_pkt.dts;

    hint_pkt.stream_index = track_index;

    if (pkt->flags & AV_PKT_FLAG_KEY)

        hint_pkt.flags |= AV_PKT_FLAG_KEY;

    if (count > 0)

        ff_mov_write_packet(s, &hint_pkt);

done:

    av_free(buf);

    sample_queue_retain(&trk->sample_queue);

    return ret;

}

void ff_mov_close_hinting(MOVTrack *track) {

    AVFormatContext* rtp_ctx = track->rtp_ctx;

    uint8_t *ptr;

    av_freep(&track->enc);

    sample_queue_free(&track->sample_queue);

    if (!rtp_ctx)

        return;

    if (rtp_ctx->pb) {

        av_write_trailer(rtp_ctx);

        url_close_dyn_buf(rtp_ctx->pb, &ptr);

        av_free(ptr);

    }

    avformat_free_context(rtp_ctx);

}