[FFmpeg-devel] [PATCH 2/2] avformat: add demuxer for Rayman 2's APM format

Paul B Mahol onemda at gmail.com
Mon Feb 17 11:26:09 EET 2020


On 2/17/20, Zane van Iperen <zane at zanevaniperen.com> wrote:
> Adds support for the APM file format used by Ubisoft's Rayman 2.
>
> Signed-off-by: Zane van Iperen <zane at zanevaniperen.com>
> ---
>  libavformat/Makefile     |   1 +
>  libavformat/allformats.c |   1 +
>  libavformat/apm.c        | 171 +++++++++++++++++++++++++++++++++++++++
>  libavformat/version.h    |   2 +-
>  4 files changed, 174 insertions(+), 1 deletion(-)
>  create mode 100644 libavformat/apm.c
>
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index a9972fd99a..e0681058a2 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -92,6 +92,7 @@ OBJS-$(CONFIG_AMRWB_DEMUXER)             += amr.o
>  OBJS-$(CONFIG_ANM_DEMUXER)               += anm.o
>  OBJS-$(CONFIG_APC_DEMUXER)               += apc.o
>  OBJS-$(CONFIG_APE_DEMUXER)               += ape.o apetag.o img2.o
> +OBJS-$(CONFIG_APM_DEMUXER)               += apm.o
>  OBJS-$(CONFIG_APNG_DEMUXER)              += apngdec.o
>  OBJS-$(CONFIG_APNG_MUXER)                += apngenc.o
>  OBJS-$(CONFIG_APTX_DEMUXER)              += aptxdec.o rawdec.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 3ea4100e85..0209bf0e30 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -53,6 +53,7 @@ extern AVInputFormat  ff_amrwb_demuxer;
>  extern AVInputFormat  ff_anm_demuxer;
>  extern AVInputFormat  ff_apc_demuxer;
>  extern AVInputFormat  ff_ape_demuxer;
> +extern AVInputFormat  ff_apm_demuxer;
>  extern AVInputFormat  ff_apng_demuxer;
>  extern AVOutputFormat ff_apng_muxer;
>  extern AVInputFormat  ff_aptx_demuxer;
> diff --git a/libavformat/apm.c b/libavformat/apm.c
> new file mode 100644
> index 0000000000..d13c2eda31
> --- /dev/null
> +++ b/libavformat/apm.c
> @@ -0,0 +1,171 @@
> +/*
> + * Rayman 2 APM Demuxer
> + *
> + * Copyright (C) 2020 Zane van Iperen (zane at zanevaniperen.com)
> + *
> + * 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 "avformat.h"
> +#include "internal.h"
> +#include "riff.h"
> +#include "libavutil/internal.h"
> +#include "libavutil/intreadwrite.h"
> +
> +#define APM_FILE_HEADER_SIZE    20
> +#define APM_VS12_CHUNK_SIZE     76
> +#define APM_MAX_READ_SIZE       4096
> +
> +typedef struct APMState {
> +    int32_t     has_saved;
> +    int32_t     predictor_r;
> +    int32_t     step_index_r;
> +    int32_t     saved_r;
> +    int32_t     predictor_l;
> +    int32_t     step_index_l;
> +    int32_t     saved_l;
> +} APMState;
> +
> +typedef struct APMVS12Chunk {
> +    uint32_t    magic;
> +    uint32_t    file_size;
> +    uint32_t    data_size;
> +    uint32_t    unk1;
> +    uint32_t    unk2;
> +    APMState    state;
> +    uint32_t    pad[7];
> +} APMVS12Chunk;
> +
> +static void apm_parse_vs12(APMVS12Chunk *vs12, const uint8_t *buf)
> +{
> +    vs12->magic                 = AV_RL32(buf + 0);
> +    vs12->file_size             = AV_RL32(buf + 4);
> +    vs12->data_size             = AV_RL32(buf + 8);
> +    vs12->unk1                  = AV_RL32(buf + 12);
> +    vs12->unk2                  = AV_RL32(buf + 16);
> +
> +    vs12->state.has_saved       = AV_RL32(buf + 20);
> +    vs12->state.predictor_r     = AV_RL32(buf + 24);
> +    vs12->state.step_index_r    = AV_RL32(buf + 28);
> +    vs12->state.saved_r         = AV_RL32(buf + 32);
> +    vs12->state.predictor_l     = AV_RL32(buf + 36);
> +    vs12->state.step_index_l    = AV_RL32(buf + 40);
> +    vs12->state.saved_l         = AV_RL32(buf + 44);
> +
> +    for (int i = 0; i < FF_ARRAY_ELEMS(vs12->pad); i++)
> +        vs12->pad[i]            = AV_RL32(buf + 48 + (i * 4));
> +}
> +
> +static int apm_read_header(AVFormatContext *s)
> +{
> +    int64_t ret;
> +    AVStream *st;
> +    APMVS12Chunk vs12;
> +    uint8_t buf[APM_VS12_CHUNK_SIZE];
> +
> +    if (!(st = avformat_new_stream(s, NULL)))
> +        return AVERROR(ENOMEM);
> +
> +    /* The header starts with a WAVEFORMATEX */
> +    if ((ret = ff_get_wav_header(s, s->pb, st->codecpar,
> APM_FILE_HEADER_SIZE, 0)) < 0)
> +        return ret;
> +
> +    if (st->codecpar->bits_per_coded_sample != 4)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (st->codecpar->codec_tag != 0x2000)
> +        return AVERROR_INVALIDDATA;
> +
> +    /* ff_get_wav_header() does most of the work, but we need to fix a few
> things. */
> +    st->codecpar->codec_id              = AV_CODEC_ID_ADPCM_IMA_APM;
> +    st->codecpar->codec_tag             = 0;
> +
> +    if (st->codecpar->channels == 2)
> +        st->codecpar->channel_layout    = AV_CH_LAYOUT_STEREO;
> +    else if (st->codecpar->channels == 1)
> +        st->codecpar->channel_layout    = AV_CH_LAYOUT_MONO;
> +    else
> +        return AVERROR_INVALIDDATA;
> +
> +    st->codecpar->format                = AV_SAMPLE_FMT_S16P;
> +    st->codecpar->bits_per_raw_sample   = 16;
> +    st->codecpar->bit_rate              = st->codecpar->channels *
> +                                          st->codecpar->sample_rate *
> +
> st->codecpar->bits_per_coded_sample;
> +
> +    if ((ret = avio_read(s->pb, buf, APM_VS12_CHUNK_SIZE)) < 0)
> +        return ret;
> +    else if (ret != APM_VS12_CHUNK_SIZE)
> +        return AVERROR(EIO);
> +
> +    apm_parse_vs12(&vs12, buf);
> +
> +    if (vs12.magic != MKTAG('v', 's', '1', '2')) {
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    if (vs12.state.has_saved) {
> +        avpriv_request_sample(s, "Saved Samples");
> +        return AVERROR_PATCHWELCOME;
> +    }
> +
> +    if (avio_rl32(s->pb) != MKTAG('D', 'A', 'T', 'A'))
> +        return AVERROR_INVALIDDATA;
> +
> +    if ((ret = ff_alloc_extradata(st->codecpar, 16)) < 0)
> +        return ret;
> +
> +    AV_WN32(st->codecpar->extradata +  0, vs12.state.predictor_l);
> +    AV_WN32(st->codecpar->extradata +  4, vs12.state.step_index_l);
> +    AV_WN32(st->codecpar->extradata +  8, vs12.state.predictor_r);
> +    AV_WN32(st->codecpar->extradata + 12, vs12.state.step_index_r);

Use same endianess as it is written in file.

> +
> +    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
> +    st->start_time  = 0;
> +    st->duration    = vs12.data_size *
> +                      (8 / st->codecpar->bits_per_coded_sample) /
> +                      st->codecpar->channels;
> +    return 0;
> +}
> +
> +static int apm_read_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> +    int ret;
> +    AVCodecParameters *par = s->streams[0]->codecpar;
> +
> +    /*
> +     * For future reference: if files with the `has_saved` field set ever
> +     * surface, `saved_l`, and `saved_r` will each contain 8 "saved"
> samples
> +     * that should be sent to the decoder before the actual data.
> +     */
> +
> +    if ((ret = av_get_packet(s->pb, pkt, APM_MAX_READ_SIZE)) < 0)
> +        return ret;
> +
> +    pkt->flags          &= ~AV_PKT_FLAG_CORRUPT;
> +    pkt->stream_index   = 0;
> +    pkt->duration       = ret * (8 / par->bits_per_coded_sample) /
> par->channels;
> +
> +    return 0;
> +}
> +
> +AVInputFormat ff_apm_demuxer = {
> +    .name           = "apm",
> +    .long_name      = NULL_IF_CONFIG_SMALL("Ubisoft Rayman 2 APM"),
> +    .read_header    = apm_read_header,
> +    .read_packet    = apm_read_packet,
> +    .extensions     = "apm"

Also add probe function.

> +};
> diff --git a/libavformat/version.h b/libavformat/version.h
> index 94fa57614d..4724269b3c 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -32,7 +32,7 @@
>  // Major bumping may affect Ticket5467, 5421, 5451(compatibility with
> Chromium)
>  // Also please add any ticket numbers that you believe might be affected
> here
>  #define LIBAVFORMAT_VERSION_MAJOR  58
> -#define LIBAVFORMAT_VERSION_MINOR  38
> +#define LIBAVFORMAT_VERSION_MINOR  39
>  #define LIBAVFORMAT_VERSION_MICRO 101

Reset micro to 0, when changing minor.


>
>  #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> --
> 2.17.1
>
>
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