remoteavformatcontext.h

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// Wrapper for AVFormatContext (av_open_input_file/stream)
// supporting myth remote files
#ifndef REMOTEAVFORMATCONTEXT_H
#define REMOTEAVFORMATCONTEXT_H
 
// C++
#include <iostream>
 
// Qt
#include <QString>
 
// MythTV
#include <libmythbase/mythlogging.h>
#include <libmythbase/remotefile.h>
 
extern "C" {
#include <libavformat/avformat.h>
#include <libavformat/avio.h>
#include <libavutil/opt.h>
}
 
class RemoteAVFormatContext
{
  public:
    explicit RemoteAVFormatContext(const QString &filename = "")
    { if (!filename.isEmpty()) Open(filename); }
 
    ~RemoteAVFormatContext()
    {
        Close();
        if (m_buffer)
            av_free(m_buffer);
    }
 
    AVFormatContext *getContext(void) { return m_inputFC; }
 
    bool Open(const QString &filename)
    {
        LOG(VB_PLAYBACK, LOG_ERR,  QString("RemoteAVFormatContext::Open: Opening %1").arg(filename));
        if (isOpen())
            return false;
 
        if (m_inputFC)
            avformat_free_context(m_inputFC);
        m_inputFC = avformat_alloc_context();
 
        delete m_rf;
 
        m_inputIsRemote = filename.startsWith("myth://");
        if (m_inputIsRemote)
        {
            m_rf = new RemoteFile(filename);
 
            if (!m_rf->isOpen())
                return false;
 
            const int BUFFER_SIZE = 0x20000;
            if (!m_buffer)
            {
                m_buffer = (unsigned char*)av_malloc(BUFFER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE);
                if (!m_buffer)
                    return false;
            }
            m_byteIOContext = avio_alloc_context(m_buffer, BUFFER_SIZE, 0,
                    m_rf, &ReadFunc, &WriteFunc, &SeekFunc);
 
            m_byteIOContext->seekable = 1;
 
            // probe the stream
            AVProbeData probe_data;
            memset(&probe_data, 0, sizeof(AVProbeData));
            probe_data.filename = "stream";
            probe_data.buf_size = m_rf->Read(m_buffer, BUFFER_SIZE);
            probe_data.buf = m_buffer;
 
            const AVInputFormat *fmt = av_probe_input_format(&probe_data, 1);
            if (!fmt)
            {
                LOG(VB_GENERAL, LOG_ERR,  QString("RemoteAVFormatContext::Open: Failed to probe file: %1").arg(filename));
                return false;
            }
            LOG(VB_PLAYBACK, LOG_INFO,  QString("RemoteAVFormatContext::Open: probed file as %1").arg(fmt->name));
 
            m_rf->Seek(0, SEEK_SET);
 
            m_inputFC->pb = m_byteIOContext;
 
            int ret = avformat_open_input(&m_inputFC, "stream", fmt, nullptr);
            if (ret)
            {
                LOG(VB_GENERAL, LOG_ERR,  QString("RemoteAVFormatContext::Open: Failed to open input: %1").arg(filename));
                return false;
            }
        }
        else
        {
            // if this is a ice/shoutcast stream setup grabbing the inline metadata
            AVDictionary *options = nullptr;
 
            if (filename.startsWith("http://"))
                av_dict_set(&options, "icy", "1", 0);
 
            int ret = avformat_open_input(&m_inputFC,  qPrintable(filename), nullptr, &options);
            if (ret)
            {
                LOG(VB_GENERAL, LOG_ERR,  QString("RemoteAVFormatContext::Open: Failed to open input: %1").arg(filename));
                return false;
            }
        }
 
        m_isOpen = true;
        return m_isOpen;
    }
 
    void Close()
    {
        if (m_inputFC)
        {
            avformat_close_input(&m_inputFC);
            m_inputFC = nullptr;
        }
 
        delete m_rf;
        m_rf = nullptr;
 
        m_isOpen = false;
    }
 
    bool isOpen() const { return m_isOpen; }
 
    operator AVFormatContext * () const { return m_inputFC; }
    //operator AVFormatContext & () const { return m_inputFC; }
    AVFormatContext * operator -> () const { return m_inputFC; }
 
  private:
    static int ReadFunc(void *opaque, uint8_t *buf, int buf_size)
    {
        auto *rf = reinterpret_cast< RemoteFile* >(opaque);
        int len = rf->Read(buf, buf_size);
        int ret = ((len == 0) && (buf_size > 0)) ? AVERROR_EOF : len;
        return ret;
    }
 
    static int WriteFunc(void */*opaque*/, const uint8_t */*buf*/, int/*buf_size*/)
    {  return -1; }
 
    static int64_t SeekFunc(void *opaque, int64_t offset, int whence)
    {
        auto *rf = reinterpret_cast< RemoteFile* >(opaque);
        if (whence == AVSEEK_SIZE)
            return rf->GetFileSize();
 
        return rf->Seek(offset, whence);
    }
 
  private:
    AVFormatContext *m_inputFC       { nullptr };
    bool             m_inputIsRemote {   false };
    bool             m_isOpen        {   false };
    RemoteFile      *m_rf            { nullptr };
    AVIOContext     *m_byteIOContext { nullptr };
    unsigned char   *m_buffer        { nullptr };
};
#endif // REMOTEAVFORMATCONTEXT_H